7. XPath Expressions in XForms
XPath expressions MUST be syntactically valid, and syntactically invalid XPath expression MUST dispatch an exception.
Test that invalid binding expression from an input control to an instance node dispatches an xforms-binding-exception
Test that use of an undefined function in a binding expression from an input control to an instance node dispatches an xforms-binding-exception
Test that invalid calculate expression in a bind element dispatches an xforms-compute-exception
Test that use of an undefined function in a calculate expression in a bind element dispatches an xforms-compute-exception
7.2 Instance Data
If the XForms processor implements DOM, then it must provide DOM access to instance data as defined by the IDL interface XFormsModelElement.
In an XForms model with an instance identified by
foo, test that getInstanceDocument("foo") returns a DOM document and that getInstanceDocument("bar") throws a DOMException.
- Create an instance with element E having three child elements, each tagged F with starting value of 1.
- Let the model declare a bind that specifies a calculate for each child of E, setting it equal to 1 more than the preceding sibling, or 1 if there is no preceding sibling.
- Let the model include a schema indicating that elements tagged F must have as content an integer less than 5.
- Declare a repeat that binds to the children of E and creates an output for each.
- Write ECMAScript that adds two F child nodes to E, then invokes rebuild(), recalculate(), revalidate() and refresh() on the instance document.
- Use a trigger to actuate the ECMAScript.
- The test is passed if two new output elements show up with values 4 and 5, and if the output with value 5 is indicated to be invalid.
Create an instance with nodes A, B, C, D. Let C have a calculate if(A < B, . + 1, .). Create an ECMAScript that modifies only D, then invokes recalculate(), revalidate(), refresh(). Test that the outputs bound to C and D both change. This proves that a
full recalculate is run since C is not dependent on what changed (D).
7.3 Evaluation Context
Every XPath expression must have the evaluation context defined by XForms.
Rule 1: Evaluation context for outermost binding elements, including a bind element and an output element.
Rule 2: Evaluation context for non-outermost binding elements, including a nested bind element and an output element inside a group element.
Rule 3: Define three XForms models identified as M1, M2 and M3 in document order. Create three outputs, the first with no model attribute, the second with a model of M2 and the third with no model attribute but within a group that has a model of M3. Bind each output to the root instance element, and set the content of the instance element equal to the model number (1, 2 or 3). The test is passed if the respective outputs display 1, 2 and 3.
Rule 4: Create an instance with multiple Line elements each containing children Units, Price, Subtotal. Set the Units and Price of each Line to mutually distinct positive numbers. Write a bind with nodeset="Line/Subtotal" and calculate="../Units * ../Price". Use a repeat to create an output for each Subtotal in the instance. Ensure each Subtotal becomes equal to the product of its sibling element Units and Price. NOTE: RULE IS INCORRECT; IT SHOULD SAY THAT for each node N in the nodeset identified by the bind element's nodeset attribute, a computed expression is evaluated with N as the context node.
Rule 5: Create an instance whose root element contains three children. Write a bind that attaches to all the children and assigns a calculate of position()+size(). Bind outputs to each child and ensure that the outputs display 4, 5 and 6. The size() is uniformly 3 and the position() varies from 1 to 3. NOTE: SPEC IS INCORRECT; IT SHOULD SAY THAT THE POSITION IS PROPERLY SET, NOT THAT IT IS UNIFORMLY 1.
Rule 6: NO TEST.
Rule 7: Tested in 7.11 Extension Functions
Rule 8: Create an instance whose Root element node declares a default namespace of http://example.org. Create a bind element that declares xmlns:ex to be equal to http://example.org and which assigns readonly of true() to the ex:Root element. Create an input control that declares xmlns:ex again and also binds to ex:Root. Ensure that the input control is read only.
7.4 Bind Expressions
Binding expressions that vary based on changes of instance data structure (i.e. are "fixed") report correct values. NOTE: THE SPEC INCORRECTLY RESTRICTS TO LOCATIONPATH, BUT MULTIPLE INSTANCES DO NOT WORK IF THIS IS THE CASE.
Binding expressions tests of position(), last(), count(), index() and property() before and after inserting a new node into instance data.
7.4.1 Model Binding Expressions
XForms processor must dispatch xforms-binding-exception and terminate when a dynamic dependency is detected in a model binding expression.
Create an instance containing two 'message' elements with 'for' attributes having different values. Create a third element whose calculation obtains the value of the first message based on matching its 'for' attribute value (e.g. calculate='message[@for="Roland"]'). Use setvalue() action to change values of the two 'for' attributes such that the first message has a 'for' attribute of "John" and the second message has a 'for' attribute of "Roland". The xforms-binding-exception must be dispatched.
7.4.2 UI Binding Expressions
XForms full processor MUST support dynamic dependencies in UI binding expressions.
Create an input control whose ref contains a value test in a predicate (e.g. ref='message[@for="Roland"]').
7.5 XForms Core Function Library
All XForms-specific functions MUST be implemented. (The functions are grouped by return type in Sections 7.6 through 7.10)
7.6 Boolean Methods
7.7 Number Methods
7.8 String Methods
7.9 Date and Time Functions
7.10 Node-set Functions
7.11 Extension Functions
If additional XPath functions are specified in the functions attribute of the model element, then the functions MUST be available to XPath expressions.
Tested in Section 3.3.1 The model Element