3.1 Constructs
3.1.1 Database
Each origin has an associated set of
databases. A database comprises
one or more object stores which hold the data stored
in the database.
Every database has a name which identifies it
within a specific origin. The name can be any string value, including the empty string, and
stays constant for the lifetime of the database. Each database also has a current
version. When a database is first created, its version is the empty string.
Implementations must support all names. If a implementation
uses a storage mechanism which can't handle arbitrary database names,
the implementation must use an escaping mechanism or something similar
to map the provided name to a name that it can handle.
Each database has one version at a time; a database
can't exist in multiple versions at once. The only way to change the version is using a VERSION_CHANGE
transaction.
Databases has a delete pending flag which is used during deletion. When a database is requested
to be deleted the flag is set to true and all attempts at opening the database are stalled until the database
can be deleted.
The act of opening a database creates a connection. There may be multiple
connections to a given database at any given time. Each connection has a
closePending flag which initially is set to false.
When a connection is initially created it is in opened state. The connection
can be closed through several means. If the connection is GCed
or execution context where the connection is created is destroyed (for example due to the
user navigating away from that page), the connection is closed. The connection can also be closed
explicitly using the steps for closing a database connection. When the connection is closed
the closePending flag is always set to true if it hasn't already been.
The IDBDatabase and IDBDatabaseSync
interfaces represent a connection to a database.
3.1.2 Object Store
An object store is the primary storage mechanism for storing data in a
database.
Each database contain a set of object stores. The set of object stores
can be changed, but can only be changed using a VERSION_CHANGE transactions. When a new database is
created it doesn't contain any object stores and has the empty string as version.
The object store has a list of records which hold the
data stored in the object store. Each record consists of a key and a value.
The list is sorted according to key in ascending order. There can never be multiple records in a given object
store with the same key.
Every object store has a name.
The name is unique within the database to which it belongs. Every object store also optionally has a
key generator and an optional key path.
If the object store has a key path it is said to use in-line keys. Otherwise it is said to
use out-of-line keys.
The object store can derive the key from one of three sources. Which source is used is determined
when the object store is created. The three sources are:
-
A key generator. A key generator generates a monotonically increasing numbers every time
a key is needed.
specify that generators are not shared between stores.
-
Keys can be derived via a key path.
-
Keys can also be explicitly specified when a value is stored in the object store.
The IDBObjectStore and IDBObjectStoreSync
interfaces represent a object store. Note however that multiple instances of those
interfaces representing the same object store can exist.
3.1.3 Keys
In order to efficiently retrieve records stored in an indexed database,
each record is organized according to its key. A value is said to be a valid key
if it is one of the following types:
Array JavaScript objects [ECMA-262],
DOMString [WEBIDL],
Date [ECMA-262] or float [WEBIDL].
However Arrays are only valid keys if every item in the array is defined and is
a valid key (i.e. sparse arrays can not be valid keys).
Any non-numeric properties are ignored, and thus does not affect if the Array is a valid key.
Additionally, if the value is of type float, it is only a valid key if it is not NaN.
Conforming user agents must support all valid keys as keys.
Infinite float values are valid keys. As are empty Arrays.
For purposes of comparison, all Arrays are greater than all DOMString,
Date and float values; all DOMString values are greater than all
Date and float values; and all Date values are greater than all
float values. Values of type float are compared to other float values
numerically. Values of type Date are compared to other Date values chronologically.
Values of type DOMString are compared to other values of type DOMString according
to the collation of the object store or index where the value is used as a key. Values
of type Array are compared to other values of type Array as follows:
-
Let A be the first
Array value and B be the second Array
value.
-
Let length be the lesser of A's length and B's length.
-
Let i be 0.
-
If the ith value of A is less than the ith value of
B, then A is less than B. Skip the remaining steps.
-
If the ith value of A is greater than the ith value of
B, then A is greater than B. Skip the remaining steps.
-
Increase i by 1.
-
If i is not equal to length, go back to step 4. Otherwise continue to next step.
-
If A's length is less than B's length, then A is less
than B. If A's length is greater than B's length, then
A is greater than B. Otherwise A and B are equal.
Note that Arrays that contain other Arrays are allowed as valid keys.
In this case the algorithm above runs recursively when comparing the individual values in the arrays.
As a result of the above rules, an empty Array is the lowest possible key, while positive
infinity is the highest possible key.
The terms greater than, less than and equal to is defined in the terms of
the above comparisons.
3.1.5 Key Path
A key path is a DOMString that defines how to extract a key from a value.
A valid key path is
either the empty string, a JavaScript identifier, or multiple Javascript identifiers separated by
periods (ASCII character code 46) [ECMA-262]. (Note that spaces are not allowed
within a key path.) To evaluate a key path, run the
steps for extracting a key from a value using a key path.
3.1.6 Index
It is sometimes useful to retrieve records in a object store through other means
than their key. A index allows looking up records in a object store
using properties of the values in the object stores records.
An index is a specialized persistent key-value storage and has a referenced object store.
The index has a list of records which hold the
data stored in the index. The records in an index are automatically populated whenever records in the
referenced object store are inserted, updated or deleted. There can be several indexes
referencing the same object store, in which changes to the object store cause all such indexes
to get updated.
The values in the index's records are always values of keys in the index's referenced
object store. The keys are derived from the referenced object store's values using a key path.
If a given record with key X in the object store referenced by the index has the value A, and
evaluating the index's key path on A yields the result
Y, then the index will contain a record with key Y and value X.
Records in an index are said to have a referenced value. This is the value of the record in the index's referenced
object store which has a key equal to the index's record's value. So in the example above,
the record in the index whose key is Y and value is X has a referenced value of A.
Each record in an index reference one and only one record in the index's referenced
object store. However there can be
multiple records in an index which reference the same record
in the object store. And there can also be no records in an index
which reference a given record in an object store.
The records in an index are always sorted according to the records key. However unlike object stores,
a given index can contain multiple records with the same key. Such records are additionally sorted according to
the records value.
An index contains a unique flag. When this flag is set to true, the index enforces that no two records
in the index has the same key. If a record
in the index's referenced object store is attempted to be inserted or
modified such that evaluating the index's key path on the
records new value yields a result which already exists in the
index, then the attempted modification to the object store
fails.
An index also contains a multirow flag. This flag affects how the index behaves when the result of evaluating
the index's key path yields an Array. If the multirow flag is false, then
a single record whose key is an Array is added to the index. If the multirow flag is
true, then the one record is added to the index for each item in the Array. The key for each
record is the value of respective item in the Array.
The IDBIndex and IDBIndexSync interfaces
provide access to the metadata of an index. Note however that multiple instances of those
interfaces representing the same index can exist.
3.1.7 Transaction
A transaction is used to interact with the data in a database.
Whenever data is read or written to the database this is done using a transaction.
All transactions are created using a connection, which is the transactions
connection.
The transaction has a mode which determines which types of interactions can be performed
using the transaction. The mode is set when the transaction is created and remains
constant for the lifetime of the transaction. The transaction also has a scope which
determines which object stores the transaction can interact with. Finally, transactions
have a active flag, which determines if new requests can currently be placed
against the transaction. Finally, transactions also contain a request list of
requests which have been placed against the transaction.
Transactions have a constant scope which is determined when the transaction is created and remains
constant for the lifetime of the transaction.
Transactions offer some protection from
application and system failures. A transaction may be used to
store multiple data records or to conditionally modify certain data
records. A transaction represents an atomic and durable set
of data access and mutation operations.
Transactions are expected to be short lived. This is encouraged
using the automatically committing functionality described below. Authors can still cause
transactions to run for a long time, however this is generally not a usage pattern which
is recommended and can lead to bad user experience in some implementations.
The lifetime of a transaction is as follows:
-
A transaction is created using
IDBDatabase.transaction.
The arguments passed determine what the scope of the transaction is and whether it's read only or not.
When a transaction is created its active flag is initially set to true.
-
The implementation must allow requests to be placed against the transaction
whenever the active flag is true. This is the case even if the transaction has not yet been
started. Until the transaction is started
the implementation must not execute these requests, but the implementation must still keep track of the
requests and their order. Requests may only be placed against the transaction while the transaction
is active. If a request is attempted to be placed against a transaction when it is not
active, the implementation must reject the attempt by throwing a TRANSACTION_INACTIVE_ERR exception.
-
Once an implementation is able to enforce the constraints defined for the mode of
the transaction, defined below, the implementation must asynchronously
start the transaction. When this happens is affected
by the mode in which the transaction is opened, and which object stores are
included in scope of the transaction.
-
Once the transaction has been started the implementation can
start executing the requests placed against the transaction. Unless otherwise defined requests
must be executed in the order they are placed against the transaction. Likewise, their result must
be returned in the order the request was placed against a specific transaction.
There is no guarantee about the order that results from requests in different transactions are returned.
Similarly, the isolation mode ensure that it doesn't matter which order requests placed against
different transactions are executed.
-
At any time a transaction can be aborted, even if the transaction isn't currently
active. When a transaction is aborted the implementation must undo (roll back) any changes
made to the database using the transaction. This includes both changes to the contents of
object stores as well as additions and removals of object stores and indexes.
A transaction can be aborted at any time before it is finished.
Including if it isn't active or hasn't yet
started.
-
Once a transaction no longer can become active, and if the transaction
hasn't been aborted, the implementation must automatically attempt to
commit it. This usually happens after all requests placed against the
transaction has been executed and their returned results handled, but no new requests has been placed
against the transaction. When a transaction is committed implementation must atomically write
any changes to the database made by requests placed against the transaction. That is, either all
of the changes must be written, or if an error occurs, such as a disk write error, the implementation
must not write any of the changes to the database. If such an error occurs the implementation must
abort the transaction by following the steps for aborting a transaction, otherwise it
must commit the transaction by following the steps for committing a transaction.
-
When a transaction is committed or aborted, it is said to be
finished. If a transaction can't be finished, for example
due to the implementation crashing or the user taking some explicit action to cancel it, the
implementation must abort the transaction.
Transactions are opened in one of three modes. The mode
determine how concurrent access to object stores in the transaction is isolated.
READ_ONLYREAD_WRITEVERSION_CHANGE
The transaction mode determines both which operations are allowed to be performed
during the transaction, as well whether two transactions can run concurrently or not.
Which operations are allowed be be performed are defined in detail below, but in general
transactions opened in READ_ONLY mode are only allowed to perform
reading operations which does not change data. READ_WRITE transactions are allowed to
perform reading and writing transactions to existing object stores, where as
VERSION_CHANGE transactions are allowed to perform any operations, including ones that
delete and create object stores and indexes.
A VERSION_CHANGE transaction can never run concurrently with other transactions. When
a VERSION_CHANGE transaction is created, the implementation must wait to
start the VERSION_CHANGE transaction until no other transactions
against the same database are running. As long as the VERSION_CHANGE transaction, the implementation
must wait with starting any other transactions against the same database
until the VERSION_CHANGE transaction is finished.
Any number of transactions opened in READ_ONLY mode are allowed to run concurrently,
even if the transaction's scope overlap and include the same object stores.
As long as a READ_ONLY transaction is running, the data that the implementation returns
through requests created with that transaction must remain
constant. That is, two requests to read the same piece of data must yield the same result
both for the case when data is found and the result is that data, and for the case when data
is not found and a lack of data is indicated.
There are a number of ways that an implementation ensure this. It can prevent
READ_WRITE transactions whose scope overlap the scope of the READ_ONLY transaction from
starting until the READ_ONLY transaction is finished. Or it can allow the READ_ONLY
transaction to see a snapshot of the contents of the object stores which is taken when
the READ_ONLY transaction is started.
Similarly, implementations must ensure that a READ_WRITE transaction is only affected by
changes to object stores that are made using the transaction itself. I.e. the
implementation must ensure that another transaction does not modify the contents of
object stores in the READ_WRITE transactions scope. The implementation
must also ensure that if the READ_WRITE transaction completes successfully, that the
changes written to object stores using the transaction can be committed to the
database without merge conflicts. An implementation must not abort a transaction
due to merge conflicts.
An implementation must not start any transaction until all other READ_WRITE transactions
with overlapping scope have completed. When multiple transactions are
eligible to be started, older transactions should be started first.
User agents must ensure a reasonable level of fairness across transactions to prevent
starvation. For example if multiple READ_ONLY transaction are started one after another
the implementation must ensure that that doesn't indefinitely prevent a pending READ_WRITE
transaction from starting.
Conforming user agents must automatically abort a transaction at
the end of the scope in which it was created, if an exception is propagated to that scope.
Transaction objects implement the
IDBTransaction or the
IDBTransactionSync interfaces.
3.1.9 Key Range
Records can be retrieved from object stores and indexes
using either keys or key ranges. A
key range is a continuous interval over some data type
used for keys.
A key range may be lower-bounded or upper-bounded if there is
a value that is, respectively, smaller than or larger than all its
elements. A key range is said to be bounded if it is both
lower- and upper-bounded and unbounded otherwise. A key range may be open,
i.e., not including its endpoints or closed, i.e., including
its endpoints. A key range may consist of a single value.
The IDBKeyRange interface defines a
key range.
interface IDBKeyRange {
readonly attribute any lower;
readonly attribute any upper;
readonly attribute boolean lowerOpen;
readonly attribute boolean upperOpen;
static IDBKeyRange only (in any value) raises (IDBDatabaseException);
static IDBKeyRange lowerBound (in any bound, in optional boolean open) raises (IDBDatabaseException);
static IDBKeyRange upperBound (in any bound, in optional boolean open) raises (IDBDatabaseException);
static IDBKeyRange bound (in any lower, in any upper, in optional boolean lowerOpen, in optional boolean upperOpen) raises (IDBDatabaseException);
};
Attributes
lower of type any, readonly- This value is the lower-bound of the key range.
No exceptions.
lowerOpen of type boolean, readonly- Returns false if the lower-bound value is included in the key range.
No exceptions.
upper of type any, readonly- This value is the upper-bound of the key range.
No exceptions.
upperOpen of type boolean, readonly- Returns false if the upper-bound value is included in the key range.
No exceptions.
Methods
bound- Creates and returns a new key range with lower set to lower,
lowerOpen set to lowerOpen, upper set to upper and
upperOpen set to upperOpen.
| Parameter |
Type |
Nullable |
Optional |
Description |
| lower |
any |
✘ |
✘ |
The lower-bound value |
| upper |
any |
✘ |
✘ |
The upper-bound value |
| lowerOpen |
boolean |
✘ |
✔ |
Is the lower-bound value included in the key range. Defaults to false. |
| upperOpen |
boolean |
✘ |
✔ |
Is the upper-bound value included in the key range. Defaults to false. |
| Exception |
Description |
IDBDatabaseException |
DATA_ERR |
Either the lower or upper parameters were not passed a valid key
or the lower key is greater than the upper key or the lower key and upper key match and either of the bounds are open. |
|
lowerBound-
Creates and returns a new key range with lower set to
lower, lowerOpen set to open,
upper set to
undefined and
and upperOpen set to true.
| Parameter |
Type |
Nullable |
Optional |
Description |
| bound |
any |
✘ |
✘ |
The lower bound value |
| open |
boolean |
✘ |
✔ |
Is the lower-bound value included in the key range. Defaults to false. |
only-
Creates and returns a new key range with both lower and
upper set to value and both
lowerOpen and upperOpen
set to false.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The only value |
upperBound-
Creates and returns a new key range with lower set to
undefined, lowerOpen set to true,
upper set to value and
and upperOpen set to open.
| Parameter |
Type |
Nullable |
Optional |
Description |
| bound |
any |
✘ |
✘ |
The upper bound value |
| open |
boolean |
✘ |
✔ |
Is the upper-bound value included in the key range. Defaults to false. |
A key is in a key range if both the following conditions are
fulfilled:
3.1.10 Cursor
Cursors are a transient mechanism used to
iterate over multiple records in a database. The storage operations
are performed on the underlying index or an
object store.
A cursor comprises a range of records in either an index
or an object store. The cursor has a source indicating
which index or object store whose records it is iterating. A cursor maintains a position over
this series, which moves in a direction that is either
monotonically increasing or decreasing order of the record keys. Cursors
also have a key and a value
which represent the key and the value of the last iterated record.
Cursors finally have a got value flag. When this flag is false, the cursor is either
in the process of loading the next value or it has reached the end of its range, when it
is true, it indicates that the cursor is currently holding a value and that it is ready to iterate
to the next one.
If the source of a cursor is a object store, the effective object store
of the cursor is that object store and the effective key of the cursor is the cursors position.
If the source of a cursor is a index, the effective object store
of the cursor is that index's referenced object store and the effective key is the cursors
object store position.
It is possible for the list of records which the cursor is iterating over to
change before the full range of the cursor has been iterated. In order to
handle this, cursors maintain their position not as an index, but rather
as a key of the previously returned record. For a forward iterating cursor,
the next time the cursor is asked to iterate to the next record it returns the
record with the lowest key greater than the one previously returned. For
a backwards iterating cursor, the situation is opposite and it returns the record
with the highest key less than the one previously returned.
For cursors iterating indexes the situation is a little bit more complicated since
multiple records can have the same key and are therefor also sorted by value.
When iterating indexes the cursor's also has a object store position, which indicates
the value of the previously found record in the index. Both
position and the object store position is used when finding the next appropriate record.
Cursor objects implement the IDBCursor
or the IDBCursorSync interfaces. There is only ever one
IDBCursor or IDBCursorSync instance representing
a given cursor. However there is no limit on how many cursors can be used at the
same time.
3.1.12 Options Object
Options objects are simply JavaScript objects [ECMA-262]
which are used to supply optional parameters to some indexedDB functions like
createObjectStore and
createIndex. The attributes on the object
correspond to optional parameters on the function called. The domain of valid
attributes/parameters depends on the function called. If an attribute is present in the
object which is not part of that domain, a
NON_TRANSIENT_ERR exception
must be thrown. Similarly, if any attribute has a getter function or its value is an object, a
NOT_TRANSIENT_ERR exception must be thrown.
We disallow getters and objects because the getter function and the toString function can
execute arbitrary JavaScript which exposes many obscure corner cases which aren't worth speccing
out. For example, navigating the page or adding an objectStore while
inside a createObjectStore call.
This should probably be moved into the WebIDL spec.
3.2 Asynchronous APIs
The asynchronous API methods return without blocking the calling thread.
All asynchronous operations immediately return an IDBRequest instance.
This object does not initially contain any information about the result of the operation.
Once information becomes available, an event is fired on the request and the information becomes
available thorugh the properties of the IDBRequest instance.
3.2.1 The IDBRequest Interface
The IDBRequest interface provides means to access results of
asynchronous requests to databases and database
objects using event handler attributes [DOM-LEVEL-3-EVENTS].
In the following example, we open a database asynchronously. Various
event handlers are registered for responding to various situations.
ECMAScript
var request = indexedDB.open('AddressBook', 'Address Book');
request.onsuccess = function(evt) {...};
request.onerror = function(evt) {...};
interface IDBRequest : EventTarget {
readonly attribute any result getraises (IDBDatabaseException);
readonly attribute unsigned short errorCode getraises (IDBDatabaseException);
readonly attribute Object source;
readonly attribute IDBTransaction transaction;
const unsigned short LOADING = 1;
const unsigned short DONE = 2;
readonly attribute unsigned short readyState;
attribute Function onsuccess;
attribute Function onerror;
};
Attributes
errorCode of type unsigned short, readonly- When the done flag is true, getting this property must return the
errorCode of the request. This is NO_ERR when no error occurred.
When the done flag is false, getting this property must throw a
NOT_ALLOWED_ERR exception.
| Exception |
On Get |
On Set |
Description |
IDBDatabaseException |
✔ |
✘ |
NOT_ALLOWED_ERR |
Thrown when this attribute was read when the done flag was set to false. |
|
onerror of type Function- The event handler for the error event
No exceptions.
onsuccess of type Function- The event handler for the success event
No exceptions.
readyState of type unsigned short, readonly- When the done flag is false, returns
LOADING,
otherwise returns DONE.No exceptions.
result of type any, readonly- When the done flag is true, getting this property must return the
result of the request. This is
undefined when the request resulted in an error.
When the done flag is false, getting this property must throw a NOT_ALLOWED_ERR exception.
| Exception |
On Get |
On Set |
Description |
IDBDatabaseException |
✔ |
✘ |
NOT_ALLOWED_ERR |
Thrown when this attribute was read when the done flag was set to false. |
|
source of type Object, readonly- Getting this property must return the source for the request.
No exceptions.
transaction of type IDBTransaction, readonly- Getting this property must return the transaction for the request.
This property can be null for certain requests, such as for request returned from IDBFactory.open and
IDBDatabase.setVersion.
No exceptions.
Constants
DONE of type unsigned short- This state indicates that a result to a previous request is available in the
result attribute.
LOADING of type unsigned short- This state indicates that a request has been started but its results is not yet available.
When a request is made, a new request is returned with its
readyState set to
LOADING.
If a request completes successfully, the
readyState
is changed to DONE, the
result
is set to the result of the request, and a event with type success is fired
at the request.
If an error occurs while performing the operation, the
readyState
is changed to DONE, the
errorCode
is set to the code of the error, and a event with type error is fired
at the request.
The setVersion function on IDBDatabase
uses a separate interface for its requests in order to make use of the
blocked event eaiser.
interface IDBVersionChangeRequest : IDBRequest {
attribute Function onblocked;
};
Attributes
onblocked of type Function- The event handler for the
blocked eventNo exceptions.
The task source for these tasks is the
database access task source.
3.2.2 Event interfaces
This specification fires events with the following custom interfaces:
interface IDBVersionChangeEvent : Event {
readonly attribute DOMString version;
};
3.2.3 Opening a database
Window and
WorkerUtils objects
must implement the IDBEnvironment interface.
Window implements IDBEnvironment;
WorkerUtils implements IDBEnvironment;
[NoInterfaceObject]
interface IDBEnvironment {
readonly attribute IDBFactory indexedDB;
};
Attributes
indexedDB of type IDBFactory, readonly- This attribute provides applications a mechanism for accessing capabilities of indexed databases.
No exceptions.
Every method for making asynchronous requests returns an
IDBRequest object that communicates back to the requesting
application through events.
This design means that any number of requests can be active on any database
or object handle at a time.
interface IDBFactory {
IDBRequest open (in DOMString name);
IDBRequest deleteDatabase (in DOMString name);
int cmp (in any first, in any second) raises (IDBDatabaseException);
};
Methods
cmp-
When invoked, this method must compare two keys. It'll return -1 if the first key is
greater than the second, 1 if the first is less than the second, and 0 if
the first is equal to the second.
This should probably take a collation parameter as well. In fact, it might make sense for this
to be on the IDBDatabase, IDBObjectStore, and IDBIndex as well and do the comparison with their
default collation.
| Parameter |
Type |
Nullable |
Optional |
Description |
| first |
any |
✘ |
✘ |
The first key to compare. |
| second |
any |
✘ |
✘ |
The second key to compare. |
deleteDatabase-
When invoked, this method must create a request and return it. The created
request has no source.
The method then asynchronously runs the steps for deleting a database.
Let origin be the origin of the IDBEnvironment used to access
this IDBFactory and name be the name parameter passed
to this function.
If an error is returned from the steps above, the implementation must set the
errorCode of the request
to the code of the error returned and fire a error event at the request.
If the steps above are successful, the implementation must set the
result of the request
to null and fire a success event at
the request.
No exceptions.
open-
When invoked, this method must create a request and return it. The created
request has no source.
The method then asynchronously runs the steps for opening a database.
Let origin be the origin of the IDBEnvironment used to access
this IDBFactory and name be the name parameter passed
to this function.
If an error is returned from the steps above, the implementation must set the
errorCode of the request
to the code of the error returned and fire a error event at the request.
If the steps above are successful, the implementation must set the
result of the request
to the connection created by the steps above and fire a success event at
the request.
No exceptions.
3.2.4 Database
A database object can be used to manipulate the
objects of that database. That is also the only way to
obtaining a transaction for that database.
interface IDBDatabase : EventTarget {
readonly attribute DOMString name;
readonly attribute DOMString version;
readonly attribute DOMStringList objectStoreNames;
IDBObjectStore createObjectStore (in DOMString name, in optional Object optionalParameters) raises (IDBDatabaseException);
IDBRequest deleteObjectStore (in DOMString name) raises (IDBDatabaseException);
IDBVersionChangeRequest setVersion ([TreatNullAs=EmptyString] in DOMString version);
IDBTransaction transaction (in any storeNames, in optional unsigned short mode) raises (IDBDatabaseException);
void close ();
attribute Function onabort;
attribute Function onerror;
attribute Function onversionchange;
};
Attributes
name of type DOMString, readonly- On getting, this attribute must return the name of the
connected database.
The function must return this name even if the closePending flag is set on the
connection. In other words, the return value from this function stays constant for the lifetime of the
IDBDatabase instance. No exceptions.
objectStoreNames of type DOMStringList, readonly- On getting, this attribute must return a list of names of the object stores
currently in the connected database.
Once the closePending flag is set on the connection,
this function must return a snapshot of the list of names of the object stores taken at the time when the
close method was called. Even if other connections are later used to change the set of
object stores that exist in the database.
In other words, the return value from this function stays constant for the lifetime of the
IDBDatabase instance, unless
setVersion and createObjectStore or deleteObjectStore
is called on this IDBDatabase instance itself. No exceptions.
onabort of type Function- The event handler for the abort event.
No exceptions.
onerror of type Function- The event handler for the error event.
No exceptions.
onversionchange of type Function- The event handler for the versionchange event.
No exceptions.
version of type DOMString, readonly- On getting, this attribute must return the version of this
database. This attribute has the empty string value when the
connected database is first created.
Once the closePending flag is set on the connection,
this function must return a snapshot of the version taken when the
close method was called.
Even if other connections are later used to change the version of the
database. In other words, the return value from this function stays constant for the lifetime of the
IDBDatabase instance, unless setVersion is called on this
IDBDatabase instance itself. No exceptions.
Methods
close- This method returns immediately and performs the steps for closing a database connection.
No parameters.
No exceptions.
createObjectStore-
This method creates and returns a new object store with the given name in the
connected database.
If this function is called from outside a VERSION_CHANGE transaction callback,
the implementation must throw a NOT_ALLOWED_ERR exception. If an objectStore with the same name already exists,
the implementation must throw a CONSTRAINT_ERR exception. Otherwise, the implementation must
create a new object store and return a IDBObjectStore object representing it.
If the optionalParameters argument is specified and has a keyPath property
which is not undefined or null, then set keyPath to the value
of this property. If keyPath is an Array, then each item in the array is
converted to a string. If keyPath is not an Array, it is converted to a
string.
If keyPath is an Array and any items in the array is not a valid key path,
or if keyPath is a string and is not a valid key path then a
NON_TRANSIENT_ERR error must be thrown. Otherwise set the created object store's
key path is set to the value of keyPath.
In some implementations it's possible for the implementation to asynchronously run into problems
creating the object store after the createObjectStore function has returned. For example in
implementations where metadata about the newly created objectStore is inserted into the database
asynchronously, or where the implementation might need to ask the user for permission for quota
reasons. Such implementations must still create and return a IDBObjectStore object. Instead,
once the implementation realizes that creating the objectStore has failed, it must abort the transaction
using the steps for aborting a transaction.
deleteObjectStore-
This method destroys the object store with the given name in the
connected database as well as
all indexes that are
referencing that object store.
Note that this method must only be called from a VERSION_CHANGE
transaction callback.
setVersion- This method updates the version of the database by following the
steps for running a
VERSION_CHANGE transaction
using the version argument as version and the IDBDatabase this function was called on as connection.
Return the IDBVersionChangeRequest returned by those steps.
No exceptions.
transaction-
This method, when called must execute the
steps for creating a transaction in a asychronous
fashion. The storeNames and mode arguments are
forwarded to the algorithm as-is. The callback argument is set to null.
The timeout argument is set to infinite.
The connection argument is set to the IDBDatabase that the
transaction() method was called on.
The method returns a IDBTransaction object representing the transaction
returned by the steps above.
| Exception |
Description |
IDBDatabaseException |
NOT_ALLOWED_ERR |
The close() method has been called on this IDBDatabase instance. |
NOT_FOUND_ERR |
One of the names provided in the storeNames argument doesn't exist in this database. |
|
3.2.5 Object Store
Object store objects implement the following
interface:
interface IDBObjectStore {
readonly attribute DOMString name;
readonly attribute DOMString keyPath;
readonly attribute DOMStringList indexNames;
readonly attribute IDBTransaction transaction;
IDBRequest put (in any value, in optional any key) raises (IDBDatabaseException, DOMException);
IDBRequest add (in any value, in optional any key) raises (IDBDatabaseException, DOMException);
IDBRequest delete (in any key) raises (IDBDatabaseException);
IDBRequest get (in any key) raises (IDBDatabaseException);
IDBRequest clear () raises (IDBDatabaseException);
IDBRequest openCursor (in optional any range, in optional unsigned short direction) raises (IDBDatabaseException);
IDBIndex createIndex (in DOMString name, in DOMString keyPath, in optional Object optionalParameters) raises (IDBDatabaseException);
IDBIndex index (in DOMString name) raises (IDBDatabaseException);
void deleteIndex (in DOMString indexName) raises (IDBDatabaseException);
};
Attributes
indexNames of type DOMStringList, readonly- On getting, provide a list of the names of indexes on objects in this object store.
No exceptions.
keyPath of type DOMString, readonly- On getting, provide the key path of this
object store.
If this attribute is
null, the application must provide a key value for each modification operation.
No exceptions.
name of type DOMString, readonly- On getting, provide the name of this object store.
No exceptions.
transaction of type IDBTransaction, readonly- On getting, returns the transaction this object store belongs to.
No exceptions.
Methods
add-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStore belongs to is
has its mode set to READ_ONLY. If any of the following conditions are true, this method
throws a DATA_ERR exception:
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
asynchronously executing a request and returns the IDBRequest created by these steps.
The steps are run with this IDBObjectStore as source and the steps for
storing a record into an object store as operation, using this IDBObjectStore
as store, the created clone as value, the key parameter as
key, and with the no-overwrite flag flag set to true.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ | ✘ |
The value to be stored in the record |
| key |
any |
✘ |
✔ |
The key used to identify the record |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this
IDBObjectStore belongs to is not active. |
READ_ONLY_ERR |
The mode of the associated transaction is
READ_ONLY. |
DATA_ERR |
The calculated key for the insertion was not a valid key.
Also thrown if the calculated key for any of the indexes which belong to this object store had a calculated key which was not a
valid key |
|
| DOMException |
DATA_CLONE_ERR |
The data being stored could not be cloned by the internal structured cloning algorithm. |
|
clear-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStore belongs to is
has its mode set to READ_ONLY.
Otherwise this method runs the steps for asynchronously executing a request and returns the
IDBRequest created by these steps. The steps are run with this IDBObjectStore as
source and the steps for clearing an object store as operation, using
this IDBObjectStore as store.
No parameters.
createIndex-
This method creates and returns a new index with the given name and parameters in the
connected database. If this function is called from
outside a VERSION_CHANGE transaction callback, the implementation
must throw a NOT_ALLOWED_ERR exception. If an index with the same name already
exists, the implementation must throw a CONSTRAINT_ERR exception. Otherwise, the implementation
must create a new index and return a IDBIndex object representing it. The created
index has its unique and multirow flags are set to the values of the
unique and multirow properties in the optionalParameters argument.
If the keyPath argument is an Array, then each item in the array is
converted to a string. If keyPath is not an Array, it is converted to a
string.
If keyPath is an Array and any items in the array is not a valid key path,
or if keyPath is a string and is not a valid key path, or if keyPath is
and Array and the multirow property in the optionalParameters is true,
then a NON_TRANSIENT_ERR error must be thrown. Otherwise set the created object store's
key path is set to the value of keyPath.
The index that is requested to be created can contain constraints on the data allowed in the index's
referenced object store, such as requiring uniqueness of the values referenced by the
index's keyPath. If the referenced object store already contains data which violates these
constraints, this must not cause the implementation of createIndex to throw an exception or affect what it returns.
The implementation must still create and return a IDBIndex object.
Instead the implementation must asynchronously abort the VERSION_CHANGE
transaction which was used for the createIndex call.
In some implementations it's possible for the implementation to asynchronously run into problems
creating the index after the createIndex function has returned. For example in
implementations where metadata about the newly created index is inserted into the database
asynchronously, or where the implementation might need to ask the user for permission for quota
reasons. Such implementations must still create and return a IDBIndex object. Instead,
once the implementation realizes that creating the index has failed, it must abort the transaction
using the steps for aborting a transaction.
| Parameter |
Type |
Nullable |
Optional |
Description |
| name |
DOMString |
✘ |
✘ |
The name of a new index |
| keyPath |
DOMString |
✘ |
✘ |
The key path used by the new
index |
| optionalParameters |
Object |
✘ |
✔ |
The options object whose attributes are optional parameters to this function.
The valid options are unique and multirow. unique specifies whether the index's
unique flag is set. It defaults to false.
multirow specifies whether the index's multirow flag is set.
It defaults to false. |
delete-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStore belongs to is
has its mode set to READ_ONLY. If the key parameter is not a valid key
this method throws a DATA_ERR exception.
Otherwise this method runs the steps for
asynchronously executing a request and returns the IDBRequest created by these steps.
The steps are run with this IDBObjectStore as source and the steps for deleting
a record from an object store as operation, using this IDBObjectStore
as store and the key parameter as key.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be deleted |
deleteIndex-
This method destroys the index with the given name in the
connected database. Note that this
method must only be called from a VERSION_CHANGE
transaction callback.
| Parameter |
Type |
Nullable |
Optional |
Description |
| indexName |
DOMString |
✘ |
✘ |
The name of an existing index |
get-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. Otherwise, this method runs the steps for asynchronously executing
a request and returns the IDBRequest created by these steps. The steps are run with this
IDBObjectStore as source and the steps for retrieving a value from an
object store as operation, using this IDBObjectStore as store and the
key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved.
This can also be a IDBKeyRange in which case the function retreives the first existing value in that range. |
index-
Returns a
IDBIndex representing a index that is part of the
to this object store. Every call to this function on the same
IDBObjectStore instance and with the same name returns the same IDBIndex instance.
However the retured IDBIndex instance is specific to this IDBObjectStore instance. If this
function is called on a different IDBObjectStore instance, a different IDBIndex instance is
returned. A result of this is that different IDBTransactions use different IDBIndex instances
to represent the same index.
| Parameter |
Type |
Nullable |
Optional |
Description |
| name |
DOMString |
✘ |
✘ |
The name of an existing index |
openCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor. The cursor
must implement the IDBCursorWithValue interface.
The newly created cursor must have an undefined position, a direction set to the value
of the direction parameter, false as iterable flag value, and undefined
key and value. The source
of the cursor is the IDBObjectStore this function was called on.
If the range parameter is a key range then the cursor's range must be set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for asynchronously executing a request and returns the IDBRequest
created by these steps. The steps are run with this IDBObjectStore as source and the
steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key.
put-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStore belongs to is
has its mode set to READ_ONLY. If any of the following conditions are true, this method
throws a DATA_ERR exception:
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
asynchronously executing a request and returns the IDBRequest created by these steps.
The steps are run with this IDBObjectStore as source and the steps for
storing a record into an object store as operation, using this IDBObjectStore
as store, the created clone as value, the key parameter as
key, and with the no-overwrite flag flag set to false.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The value to be stored in the record |
| key |
any |
✘ |
✔ |
The key used to identify the record |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this IDBObjectStore
belongs to is not active. |
READ_ONLY_ERR |
The mode of the associated transaction is READ_ONLY. |
DATA_ERR |
The calculated key for the insertion was not a valid key.
Also thrown if the calculated key for any of the indexes which belong to this object store had a calculated key which was not a
valid key |
|
| DOMException |
DATA_CLONE_ERR |
The data being stored could not be cloned by the internal structured cloning algorithm. |
|
3.2.6 Index
Index objects implement the following interface:
interface IDBIndex {
readonly attribute DOMString name;
readonly attribute IDBObjectStore objectStore;
readonly attribute DOMString keyPath;
readonly attribute boolean unique;
IDBRequest openCursor (in optional IDBKeyRange range, in optional unsigned short direction) raises (IDBDatabaseException);
IDBRequest openKeyCursor (in optional IDBKeyRange range, in optional unsigned short direction) raises (IDBDatabaseException);
IDBRequest get (in any key) raises (IDBDatabaseException);
IDBRequest getKey (in any key) raises (IDBDatabaseException);
};
Methods
get-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. This method runs the steps for asynchronously executing a request
and returns the IDBRequest created by these steps. The steps are run with this
IDBObjectStore as source and the steps for retrieving a referenced value from an
index as operation, using this IDBIndex as index and the
key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved.
This can also be a IDBKeyRange in which case the function retreives the first existing value in that range. |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this IDBIndex belongs to is not
active. |
DATA_ERR |
The key parameter was not passed a valid value. |
|
getKey-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. This method runs the steps for asynchronously executing a request
and returns the IDBRequest created by these steps. The steps are run with this
IDBObjectStore as source and the steps for retrieving a value from an
index as operation, using this IDBIndex as index and the
key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openKeyCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved. This can also be a IDBKeyRange in which case
the function retreives the first existing value in that range. |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this IDBIndex belongs to is not
active. |
DATA_ERR |
The key parameter was not passed a valid value. |
|
openCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor. The cursor
must implement the IDBCursorWithValue interface.
The newly created cursor must have an undefined position, a direction set to the value
of the direction parameter, false as iterable flag value, and undefined
key and value. The source
of the cursor is the IDBIndex this function was called on.
If the range parameter is a key range then the cursor's range is set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for asynchronously executing
a request and returns the IDBRequest created by these steps. The steps are run with this
IDBIndex as source and the steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key
openKeyCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor.
The cursor must implement the IDBCursor interface,
but must not implement the IDBCursorWithValue interface.
The newly created cursor must have an undefined position,
a direction set to the value of the direction parameter, false as iterable flag value,
and undefined key and value.
The source
of the cursor is the IDBIndex this function was called on.
If the range parameter is a key range then the cursor's range is set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for asynchronously executing
a request and returns the IDBRequest created by these steps. The steps are run with this
IDBObjectStore as source and the steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key
3.2.7 Cursor
Cursor objects implement the following interface:
interface IDBCursor {
const unsigned short NEXT = 0;
const unsigned short NEXT_NO_DUPLICATE = 1;
const unsigned short PREV = 2;
const unsigned short PREV_NO_DUPLICATE = 3;
readonly attribute Object source;
readonly attribute unsigned short direction;
readonly attribute any key;
readonly attribute any primaryKey;
IDBRequest update (in any value) raises (IDBDatabaseException, DOMException);
void advance (in int count);
void continue (in optional any key) raises (IDBDatabaseException);
IDBRequest delete () raises (IDBDatabaseException);
};
Attributes
direction of type unsigned short, readonly- On getting, provide the traversal direction of the cursor.
No exceptions.
key of type any, readonly- Returns the cursor's current key.
However if the cursor's got value flag is false it returns
undefined.
I.e. if it's currently being iterated or has iterated past the end of its range.No exceptions.
primaryKey of type any, readonly- Returns the cursor's current effective key.
However if the cursor's got value flag is false it returns
undefined.
I.e. if it's currently being iterated or has iterated past the end of its range.No exceptions.
source of type Object, readonly- On getting, returns the
IDBObjectStore or IDBIndex
which this cursor is iterating. This function never returns null or throws an exception, even if the is currently being iterated, has iterated past its end,
or its transaction is not active. No exceptions.
Methods
advance-
This method runs the steps for asynchronously executing a request.
However, the steps are slightly modified such that instead of creating a new IDBRequest, it reuses the
request originally created when this cursor was created. The done flag
on the request is set to false before the request is returned. The steps are run with the cursor's
source as source. The operation
runs the steps for iterating a cursor count number of times
with null as key and this cursor as cursor.
| Parameter |
Type |
Nullable |
Optional |
Description |
| count |
int |
✘ |
✘ |
The number of advances forward the cursor should make. |
No exceptions.
continue-
If this cursor's got value flag is false, this method throws a NOT_ALLOWED_ERR.
If the key parameter is specified and fulfills any of these conditions this
method must throw a DATA_ERR exception:
Otherwise this method runs the steps for asynchronously executing a request.
However, the steps are slightly modified such that instead of creating a new IDBRequest, it reuses the
request originally created when this cursor was created. The done flag
on the request is set to false before the request is returned. The steps are run with the cursor's
source as source and the
steps for iterating a cursor as operation,
using this cursor as cursor and the key parameter as key.
Before this method returns, unless an exception was thrown, it sets the got value flag on the cursor to false.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✔ |
The next key to position this cursor at |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this
IDBCursor belongs to is not active. |
NOT_ALLOWED_ERR |
The cursor is currently being iterated, or has iterated past its end. |
DATA_ERR |
The key parameter was specified but did not contain a valid key. |
|
delete-
This method throws a READ_ONLY_ERR if the transaction which this IDBCursor belongs to
has its mode set to READ_ONLY. If this cursor's got value flag is false,
or if this cursor was created using
openKeyCursor a
NOT_ALLOWED_ERR is thrown.
Otherwise this method runs the steps for asynchronously executing a request and returns the
IDBRequest created by these steps.
The steps are run with this IDBCursor as source
and the steps for deleting a record from an object store as operation, using this cursor's
effective object store and effective key as store and
key respectively.
This method used to set this cursor's value to null. Do we want to keep that?
No parameters.
update-
This method throws a READ_ONLY_ERR if the transaction which this IDBCursor belongs to
has its mode set to READ_ONLY. If this cursor's got value flag is false or if this
cursor was created using
openKeyCursor. This method
throws a NOT_ALLOWED_ERR. If the effective object store of this cursor uses in-line
keys and evaluating the
key path
of the value parameter results in a different value than the cursor's effective key,
this method throws DATA_ERR.
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
asynchronously executing a request and returns the IDBRequest created by these steps.
The steps are run with this IDBCursor as source and the steps for
storing a record into an object store as operation, using this cursor's
effective object store as store, the created clone as value,
this cursor's effective key as key, and with the no-overwrite flag
flag set to false.
A result of running the steps for storing a record into an object store is that if the record
has been deleted since the cursor moved to it, a new record will be created.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The new value to store at the current position. |
Constants
NEXT of type unsigned short- indicates that this cursor should yield all records, including
duplicates and its direction is monotonically increasing
order of keys.
NEXT_NO_DUPLICATE of type unsigned short- indicates that this cursor should yield all records, not including
duplicates and its direction is monotonically increasing
order of keys. For every key with duplicate values, only the first record is yielded.
PREV of type unsigned short- indicates that cursor should yield all records, including
duplicates and its direction is monotonically decreasing
order of keys.
PREV_NO_DUPLICATE of type unsigned short- indicates that this cursor should yield all records, not including
duplicates and its direction is monotonically decreasing
order of keys. For every key with duplicate values, only the first record is yielded.
interface IDBCursorWithValue : IDBCursor {
readonly attribute any value;
};
Attributes
value of type any, readonly- Returns the cursor's current value. However if the cursor's got value
flag is false it returns
undefined. I.e. if it's currently being iterated or has
iterated past the end of its range. Note that if this property returns an object, it returns the same
object instance every time it is inspected, until the cursor is iterated. This means that if the object is modified,
those modifications will be seen by anyone inspecting the value of the cursor. However modifying such an object
does not modify the contents of the database.No exceptions.
3.3 Synchronous APIs
The synchronous database API methods provide a blocking access pattern to IndexedDB
databases. Since they block the calling thread they are only available from workers.
3.3.2 Database
A database object provides access to the schema and data of a particular database.
interface IDBDatabaseSync {
readonly attribute DOMString name;
readonly attribute DOMString version;
readonly attribute DOMStringList objectStoreNames;
IDBObjectStoreSync createObjectStore (in DOMString name, in optional Object optionalParameters) raises (IDBDatabaseException);
void deleteObjectStore (in DOMString name) raises (IDBDatabaseException);
IDBTransactionSync setVersion ([TreatNullAs=EmptyString] in DOMString version);
void transaction (in any storeNames, in IDBTransactionCallback callback, in optional unsigned short mode, in optional unsigned long timeout) raises (IDBDatabaseException);
void close ();
};
Attributes
name of type DOMString, readonly-
On getting, this attribute must return the name
of the connected database. The function must
return this name even if the closePending flag is set on the connection.
In other words, the return value from this function stays constant for the lifetime of the
IDBDatabaseSync instance.
No exceptions.
objectStoreNames of type DOMStringList, readonly-
On getting, this attribute must return a list of names of the
object stores currently in the
connected database.
Once the closePending flag is set on the connection, this
function must return a snapshot of the list of names of the object
stores taken at the time when the close method was called. Even if
other connections are later used to change the set of object
stores that exist in the database. In other words, the return
value from this function stays constant for the lifetime of the
IDBDatabaseSync instance, unless
setVersion and
createObjectStore or
deleteObjectStore
is called on this IDBDatabaseSync instance itself.
No exceptions.
version of type DOMString, readonly-
On getting, this attribute must return the version of this
database. This attribute has the empty string value when the
connected database is first created.
Once the closePending flag is set on the connection, this
function must return a snapshot of the version taken when the
close method was called. Even if
other connections are later used to change the version of the
database. In other words, the return value from this function
stays constant for the lifetime of the
IDBDatabaseSync instance,
unless setVersion is called
on this IDBDatabaseSync instance itself.
No exceptions.
Methods
close- This method synchronously performs the steps for closing a database connection and returns once
the database has been closed.
No parameters.
No exceptions.
createObjectStore-
This method creates a and returns a new object store with the
given name in the connected database. This method
should only be called from inside a VERSION_CHANGE transaction.
If the optionalParameters argument is specified and has a keyPath property
which is not undefined or null, then set keyPath to the value
of this property. If keyPath is an Array, then each item in the array is
converted to a string. If keyPath is not an Array, it is converted to a
string.
If keyPath is an Array and any items in the array is not a valid key path,
or if keyPath is a string and is not a valid key path then a
NON_TRANSIENT_ERR error must be thrown. Otherwise set the created object store's
key path is set to the value of keyPath.
deleteObjectStore-
This method destroys an object store with the
given name as well as all indexes that are
referencing that object store. This method
should only be called from inside a VERSION_CHANGE transaction.
setVersion-
This method updates the version of the database by following the
steps for running a
VERSION_CHANGE transaction using
the version argument as version and the IDBDatabaseSync
this function was called on as connection. It returns the transaction
object that should be used to perform the changes to the database required for the new version.
Processing a setVersion call may take a long time as it requires all other
connections to the database to be closed, which in turn may depend on user input or other
long-running tasks. If blocking for a long period of time is not acceptable for a given
scenario then the asynchronous API should be used for version changes.
No exceptions.
transaction-
This method, when called must execute the
steps for creating a transaction in a sychronous
fashion. The storeNames, callback, mode, and
timeout arguments are forwarded to the algorithm as-is. The connection
argument is set to the IDBDatabaseSync that the transaction() method was
called on.
The method returns a IDBTransactionSync object representing the transaction
returned by the steps above.
| Parameter |
Type |
Nullable |
Optional |
Description |
| storeNames |
any |
✘ |
✘ |
The names of object stores and
indexes in the scope of the new
transaction |
| callback |
IDBTransactionCallback |
✘ |
✘ |
A callback which will be called with the newly created transaction. When the callback returns, the transaction is committed. |
| mode |
unsigned short |
✘ |
✔ |
The mode for isolating access to data inside the given
object stores. If this parameter is not provided, the default access
mode is READ_ONLY. |
| timeout |
unsigned long |
✘ |
✔ |
The interval in milliseconds which this operation is allowed to take to reserve all the
database objects identified in the new
transaction's scope. The default is user agent specific |
| Exception |
Description |
IDBDatabaseException |
TIMEOUT_ERR |
If starting the transaction takes longer than the specified timeout. |
NOT_ALLOWED_ERR |
The close() method has been called on this IDBDatabase instance. |
NOT_FOUND_ERR |
One of the names provided in the storeNames argument doesn't exist in this database. |
|
3.3.3 Object Store
In the following example, we set up an object store to use the
key path id. This
object store is also designed to use a key generator.
ECMAScript
var db = indexedDBSync.open('AddressBook');
if (db.version !== '1') {
var vtx = db.setVersion('1');
vtx.createObjectStore('Contact', 'id', true);
}
The scenario above doesn't actually work well because you have to unwind to
the event loop to get the version transaction to commit before you can do something
else. Leaving it like this for now, as this will get sorted out when we add callbacks
for transactions in the sync API (we'll have to do it for the setVersion transaction
as well).
Using this database, we can store records in the Contact
object store.
ECMAScript
var tx = db.transaction();
var store = tx.objectStore('Contact');
var contact = store.add({name: 'Lincoln', number: '7012'});
// contact.id === 1
A stored value can be retrieved using the same key used by the
first put operation.
ECMAScript
var contact = store.get(1);
// contact.name === 'Lincoln'
A put operation will overwrite the record stored by the first
add operation with the same key.
ECMAScript
var abraham = {id: 1, name: 'Abraham', number: '2107'};
store.put(abraham);
Now when the object store is read with the same key, the result
is different compared to the object read earlier.
ECMAScript
var contact = store.get(1);
// contact.id === 1 && contact.name === 'Abraham';
Additionally, all the records of an object store
matching a certain key range can be retrieved in key order.
ECMAScript
var range = new IDBKeyRange.bound(2, 4);
var cursor = store.openCursor(range);
// each value is a contact and each key is the id for that
// contact whose id is between 2 and 4, both inclusive
cursor.continue();
interface IDBObjectStoreSync {
readonly attribute DOMString name;
readonly attribute DOMString keyPath;
readonly attribute DOMStringList indexNames;
readonly attribute IDBTransactionSync transaction;
any put (in any value, in optional any key) raises (IDBDatabaseException, DOMException);
any add (in any value, in optional any key) raises (IDBDatabaseException, DOMException);
void delete (in any key) raises (IDBDatabaseException);
any get (in any key) raises (IDBDatabaseException);
void clear () raises (IDBDatabaseException);
IDBIndexSync createIndex (in DOMString name, in DOMString keyPath, in optional Object optionalParameters) raises (IDBDatabaseException);
IDBIndexSync index (in DOMString name) raises (IDBDatabaseException);
void deleteIndex (in DOMString indexName) raises (IDBDatabaseException);
IDBCursorWithValueSync openCursor (in optional any range, in optional unsigned short direction) raises (IDBDatabaseException);
};
Attributes
indexNames of type DOMStringList, readonly-
On getting, provide a list of the names of indexes on
objects in this object store.
No exceptions.
keyPath of type DOMString, readonly-
On getting, provide the key path
of this object store. If this attribute is
null,
the application must provide a key value for each modification operation.
No exceptions.
name of type DOMString, readonly-
On getting, provide the name of this
object store.
No exceptions.
transaction of type IDBTransactionSync, readonly-
On getting, returns the transaction this object store belongs to.
No exceptions.
Methods
add-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStoreSync belongs to is
has its mode set to READ_ONLY. If any of the following conditions are true, this method
throws a DATA_ERR exception:
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
synchronously executing a request and returns the key of the stored object.
The steps are run with this IDBObjectStoreSync as source and the steps for
storing a record into an object store as operation, using this IDBObjectStoreSync
as store, the created clone as value, the key parameter as
key, and with the no-overwrite flag flag set to true.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The value to be stored in the record |
| key |
any |
✘ |
✔ |
The key used to identify the record |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this
IDBObjectStoreSync belongs to is not active. |
READ_ONLY_ERR |
The mode of the associated
transaction is READ_ONLY. |
DATA_ERR |
The calculated key for the insertion was not a valid key.
Also thrown if the calculated key for any of the indexes which belong to this object store had a calculated key which was not a
valid key |
CONSTRAINT_ERR |
A record exists in this object store for the key key parameter,
or another record in this object store has the same value for the keyPath of a unique
index. |
|
| DOMException |
DATA_CLONE_ERR |
The data being stored could not be cloned by the internal structured cloning algorithm. |
|
clear-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStoreSync belongs to is
has its mode set to READ_ONLY.
Otherwise this method runs the steps for synchronously executing a request. The steps
are run with this IDBObjectStoreSync as source and the
steps for clearing an object store as operation, using
this IDBObjectStoreSync as store.
No parameters.
createIndex-
This creates and returns a new index with the given name and parameters in the
connected database. Note that this method must only
be called from a VERSION_CHANGE transaction. The created
index has its unique and multirow flags are set to the values of the
unique and multirow properties in the optionalParameters argument.
If the keyPath argument is an Array, then each item in the array is
converted to a string. If keyPath is not an Array, it is converted to a
string.
If keyPath is an Array and any items in the array is not a valid key path,
or if keyPath is a string and is not a valid key path, or if keyPath is
and Array and the multirow property in the optionalParameters is true,
then a NON_TRANSIENT_ERR error must be thrown. Otherwise set the created object store's
key path is set to the value of keyPath.
| Parameter |
Type |
Nullable |
Optional |
Description |
| name |
DOMString |
✘ |
✘ |
The name of a new index |
| keyPath |
DOMString |
✘ |
✘ |
The key path used by the new index |
| optionalParameters |
Object |
✘ |
✔ |
The options object whose attributes are optional parameters to this function.
The valid options are unique and multirow. unique specifies whether the index's
unique flag is set. It defaults to false. multirow specifies whether the
index's multirow flag is set. It defaults to false. |
| Exception |
Description |
IDBDatabaseException |
NOT_ALLOWED_ERR |
This method was not called from a VERSION_CHANGE
transaction. |
CONSTRAINT_ERR |
An index with the same name, compared in a case-sensitive manner, already exists in the
connected database.
Also thrown when creating a unique index on top of an object store
that already contains records that violate the unique constraint. |
NON_TRANSIENT_ERR |
optionalParameters has attributes other than unique. |
|
delete-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStoreSync belongs to is
has its mode set to READ_ONLY. If the key parameter is not a valid key
this method throws a DATA_ERR exception.
Otherwise this method runs the steps for
synchronously executing a request.
The steps are run with this IDBObjectStoreSync as source and the
steps for deleting
a record from an object store as operation, using this IDBObjectStoreSync
as store and the key parameter as key.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be deleted |
deleteIndex-
This method destroys the index with the given name in the
connected database. Note that this
method must only be called from a VERSION_CHANGE
transaction.
| Parameter |
Type |
Nullable |
Optional |
Description |
| indexName |
DOMString |
✘ |
✘ |
The name of an existing index |
get-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. Otherwise, this method runs the steps for synchronously executing
a request and returns the result of the operation. The steps are run with this
IDBObjectStoreSync as source and the
steps for retrieving a value from an
object store as operation, using this IDBObjectStoreSync as store and the
key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved.
This can also be a IDBKeyRange in which case the function retrieves the first existing value in that range. |
index-
Returns a
IDBIndexSync representing a index that is part of the
to this object store. Every call to this function on the same
IDBObjectStoreSync instance and with the same name returns the same
IDBIndexSync instance. However the retured
IDBIndexSync instance is specific to this
IDBObjectStoreSync instance. If this function is called on a different
IDBObjectStoreSync instance, a different IDBIndexSync
instance is returned. A result of this is that different IDBTransactionSyncs use different
IDBIndexSync instances to represent the same index.
| Parameter |
Type |
Nullable |
Optional |
Description |
| name |
DOMString |
✘ |
✘ |
The name of an existing index |
openCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor. The cursor
must implement the IDBCursorWithValueSync interface.
The newly created cursor must have an undefined position, a direction set to the value
of the direction parameter, false as iterable flag value, and undefined
key and value. The source
of the cursor is the IDBObjectStoreSync this function was called on.
If the range parameter is a key range then the cursor's range is set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for synchronously executing a request and returns the result of the operation, in
this case an IDBCursorSync object. The steps are run with this IDBObjectStoreSync as source and the
steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key.
put-
This method throws a READ_ONLY_ERR if the transaction which this IDBObjectStoreSync belongs to
has its mode set to READ_ONLY. If any of the following conditions are true, this method throws a DATA_ERR exception:
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
synchronously executing a request and returns the result, in this case the key of the stored object.
The steps are run with this IDBObjectStoreSync as source and the steps for
storing a record into an object store as operation, using this IDBObjectStoreSync
as store, the created clone as value, the key parameter as
key, and with the no-overwrite flag flag set to false.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The value to be stored in the record |
| key |
any |
✘ |
✔ |
The key used to identify the record |
| Exception |
Description |
IDBDatabaseException |
TRANSACTION_INACTIVE_ERR |
The transaction this
IDBObjectStoreSync belongs to is not active. |
READ_ONLY_ERR |
The mode of the associated
transaction is READ_ONLY. |
DATA_ERR |
The calculated key for the insertion was not a valid key.
Also thrown if the calculated key for any of the indexes which belong to this object store had a calculated key which was not a
valid key |
CONSTRAINT_ERR |
Another record in this object store has the same value for the keyPath of a unique
index. |
|
| DOMException |
DATA_CLONE_ERR |
The data being stored could not be cloned by the internal structured cloning algorithm. |
|
3.3.4 Index
An index can be created for retrieving records other than
by using record keys. Continuing the earlier example, an
index could be maintained on the name property of objects
in the Contact object store.
The scenario above doesn't actually work well because you have to unwind to
the event loop to get the version transaction to commit before you can do something
else. Leaving it like this for now, as this will get sorted out when we add callbacks
for transactions in the sync API (we'll have to do it for the setVersion transaction
as well).
For example, the id of an object with the name
property value 'Lincoln' can be retrieved using the
ContactName index.
ECMAScript
var index = store.openIndex('ContactName');
var id = index.get('Lincoln');
// id === 1
Additionally, all the records of an object store matching
a certain range index keys can be retrieved in key order. When
objects are retrieved from the Contact object store,
they are arranged by the value of the id attribute. On the
other hand, when objects are retrieved using the ContactName
index, they are arranged by the value of the name
property.
ECMAScript
var range = new IDBKeyRange.bound('L', 'M');
var cursor = index.openCursor(range);
// each value is a contact and each key is the name for that
// contact whose name's first letter is either L or M
cursor.continue();
If, on the other hand, we only want the names and keys but not the whole Contact
objects for a given range, then we can use a different mechanism for that.
ECMAScript
var range = new IDBKeyRange.bound('L', 'M');
var cursor = index.openKeyCursor(range);
// each value is a contact id and each key is the name for that
// contact whose name's first letter is either L or M
cursor.continue();
interface IDBIndexSync {
readonly attribute DOMString name;
readonly attribute IDBObjectStoreSync objectStore;
readonly attribute DOMString keyPath;
readonly attribute boolean unique;
IDBCursorWithValueSync openCursor (in optional IDBKeyRange range, in optional unsigned short direction) raises (IDBDatabaseException);
IDBCursorSync openKeyCursor (in optional IDBKeyRange range, in optional unsigned short direction) raises (IDBDatabaseException);
any get (in any key) raises (IDBDatabaseException);
any getKey (in any key) raises (IDBDatabaseException);
};
Methods
get-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. This method runs the steps for synchronously executing a request
and returns the result from that, in this case an object from the underlying store.
The steps are run with this IDBIndexSync as source and the
steps
for retrieving a referenced value from an index as operation, using this IDBIndexSync
as index and the key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved. This can also be a IDBKeyRange in which case
the function retreives the first existing value in that range. |
getKey-
If the key parameter is not a valid key or a key range, this method
throws a DATA_ERR exception. This method runs the steps for synchronously executing a request
and returns the result from that, in this case an index value (a key).
The steps are run with the IDBObjectStoreSync associated with this index as source and the
steps for retrieving a value from an index as operation, using this
IDBIndexSync as index and the key parameter as key.
This function produces the same result if a record with the given key doesn't exist as when a record
exists, but has undefined as value. If you need to tell the two situations apart, you can use
openCursor with the same key. This will return a cursor with
undefined as value if a record exists, or no cursor if no such record exists.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✘ |
Key identifying the record to be retrieved. This can also be a IDBKeyRange in which case
the function retreives the first existing value in that range. |
openCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor.
The cursor must implement the IDBCursorWithValueSync interface.
The newly created cursor must have an undefined position,
a direction set to the value of the direction parameter, false as iterable flag value, and undefined
key and value.
The source
of the cursor is the IDBIndexSync this function was called on.
If the range parameter is a key range then the cursor's range is set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for synchronously executing
a request and returns the result, in this case a cursor object. The steps are run with this
IDBIndexSync as source and the steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key
openKeyCursor-
If the range parameter is specified but is not a valid key or a key range,
this method throws a DATA_ERR exception. Otherwise, this method creates a cursor. The cursor
must implement the IDBCursorSync interface and
must not implement the IDBCursorWithValueSync interface.
The newly created cursor must have an undefined position, a
direction set to the value
of the direction parameter, false as iterable flag value, and undefined
key and value.
The source
of the cursor is the IDBIndexSync this function was called on.
If the range parameter is a key range then the cursor's range is set to that
range. Otherwise, if the range parameter is a valid key then the cursor's range
is set to key range containing only that key value. If the range parameter is not specified,
the cursor's key range is left as undefined.
This method runs the steps for synchronously executing
a request and returns the result, in this case a cursor object. The steps are run with this
IDBIndexSync as source and the steps for iterating a cursor as operation,
using the created cursor as cursor and with undefined as key
3.3.5 Cursor
Using the synchronous API, an application can process all the records
in the cursor's range.
By default, a cursor walks over objects starting at the
first record and ending at the last record including
all the duplicates encountered along the way.
ECMAScript
var tx = db.transaction('Contact');
var store = tx.objectStore('Contact');
var cursor = store.openCursor();
while(cursor.continue()) {
var value = cursor.value;
// act on each object or key
}
To start at the last record and end in the first record, the cursor
should be created with the direction parameter PREV.
To start at a certain key and end in the last record, i.e.,
for a lower-bounded cursor, while skipping duplicates,
the cursor should be created with both the required
start key and the direction parameter.
It is also possible to create a bounded cursor, i.e., with
application-specified starting and ending points, the
cursor should be created with both the required keys.
If the range is inclusive of both keys, then additional
flags are required. In the following example, all keys
with values in the inclusive range (start,
end) are returned with all their duplicates,
from the beginning of the range to its end.
interface IDBCursorSync {
const unsigned short NEXT = 0;
const unsigned short NEXT_NO_DUPLICATE = 1;
const unsigned short PREV = 2;
const unsigned short PREV_NO_DUPLICATE = 3;
readonly attribute Object source;
readonly attribute unsigned short direction;
readonly attribute any key;
IDBRequest update (in any value) raises (IDBDatabaseException, DOMException);
void advance (in int count);
boolean continue (in optional any key) raises (IDBDatabaseException);
void delete () raises (IDBDatabaseException);
};
Attributes
direction of type unsigned short, readonly-
On getting, provide the traversal direction of the cursor.
No exceptions.
key of type any, readonly-
The key for the record at the cursor's position.
However if the cursor's got value flag is false it returns
undefined. I.e. if it's currently being iterated or has
iterated past the end of its range.No exceptions.
source of type Object, readonly-
On getting, returns the
IDBObjectStoreSync or IDBIndexSync
which this cursor is iterating. This function never returns null or throws an exception, even if the is currently being iterated, has iterated past its end,
or its transaction is not active.
No exceptions.
Methods
advance-
This method runs the steps for synchronously executing a request.
The steps are run with the cursor's source as source.
The operation runs the steps for iterating a cursor count number of times
with null as key and this cursor as cursor.
| Parameter |
Type |
Nullable |
Optional |
Description |
| count |
int |
✘ |
✘ |
The number of advances forward the cursor should make. |
No exceptions.
continue-
If this cursor's got value flag is false, this method throws a NOT_ALLOWED_ERR.
If the key parameter is specified and fulfills any of these conditions this
method must throw a DATA_ERR exception:
Otherwise this method runs the steps for synchronously executing a request.
The steps are run with the cursor's source as source and the
steps
for iterating a cursor as operation, using the cursor this is called on as cursor and
the key parameter as key.
Before this method returns, unless an exception was thrown, it sets the got value flag in the cursor to false.
| Parameter |
Type |
Nullable |
Optional |
Description |
| key |
any |
✘ |
✔ |
The next key to position this cursor at |
delete-
This method throws a READ_ONLY_ERR if the transaction which this IDBCursorSync belongs to
has its mode set to READ_ONLY. If this cursor's got value flag is false,
or if this cursor was created using
openKeyCursor a
NOT_ALLOWED_ERR is thrown.
Otherwise this method runs the steps for synchronously executing a request. The steps are run
with this IDBCursorSync as source and the
steps for deleting a record from an
object store as operation, using this cursor's effective object store and
effective key as store and key respectively.
This method used to set this cursor's value to null. Do we want to
keep that?
No parameters.
update-
This method throws a READ_ONLY_ERR if the transaction which this IDBCursorSync belongs to
has its mode set to READ_ONLY. If this cursor's got value flag is false or if this
cursor was created using openKeyCursor.
This method throws a NOT_ALLOWED_ERR. If the effective object store of this cursor uses in-line
keys and evaluating the
key path
of the value parameter results in a different value than the cursor's effective key,
this method throws DATA_ERR.
Otherwise this method creates a structured clone of the value parameter.
If this throws an exception that exception is rethrown. It then runs the steps for
synchronously executing a request and returns the result returned by these steps.
The steps are run with this IDBCursorSync as source and the steps for
storing a record into an object store as operation, using this cursor's
effective object store as store, the created clone as value,
this cursor's effective key as key, and with the no-overwrite flag
flag set to false.
A result of running the steps for storing a record into an object store is that if the record
has been deleted since the cursor moved to it, a new record will be created.
| Parameter |
Type |
Nullable |
Optional |
Description |
| value |
any |
✘ |
✘ |
The new value to store at the current position. |
Constants
NEXT of type unsigned short-
indicates that this cursor should yield all records, including
duplicates and its direction is monotonically increasing
order of keys.
NEXT_NO_DUPLICATE of type unsigned short-
indicates that this cursor should yield all records, not including
duplicates and its direction is monotonically increasing
order of keys. For every key with duplicate values, only the first
record is yielded.
PREV of type unsigned short-
indicates that cursor should yield all records, including
duplicates and its direction is monotonically decreasing
order of keys.
PREV_NO_DUPLICATE of type unsigned short-
indicates that this cursor should yield all records, not including
duplicates and its direction is monotonically decreasing
order of keys. For every key with duplicate values, only the first
record is yielded.
interface IDBCursorWithValueSync : IDBCursorSync {
attribute any value;
};
Attributes
value of type any- The value for the record at the cursor's position.
However if the cursor's got value
flag is false it returns
undefined. I.e. if it's currently being iterated or has
iterated past the end of its range. Note that if this property returns an object, it returns the same
object instance every time it is inspected, until the cursor is iterated. This means that if the object is modified,
those modifications will be seen by anyone inspecting the value of the cursor. However modifying such an object
does not modify the contents of the database.
No exceptions.