13970 2011-08-30 12:53:55 +0000 [UPD] fn:put and transform expressions 2014-10-14 09:36:16 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Update Facility Recommendation PC Windows NT CLOSED FIXED P2 normal --- 1 tim jonathan.robie christian.gruen john.snelson public-qt-comments oldest_to_newest 56039 0 tim 2011-08-30 12:53:55 +0000 Are there any special considerations when mixing fn:put with transform expressions? Example 1 --------- copy $dummy := <dummy /> modify fn:put(<new-document />, "output.xml") return local:non-updating-query() This stores an element in output.xml but also returns the result of executing a non-updating query. It seems a little unfortunate that this 'dummy' is required to mix fn:put with a non-updating query - although since this is essentially an expression with side effects, perhaps that's no bad thing. Example 2 --------- let $original := doc('update.xml') return copy $doc := $original modify (insert node <node /> into $doc/nodes, fn:put($doc, "update.xml")) return $original This example reads and writes the same resource. In XSLT, there is a specific (recoverable) error which mentions a similar situation with xsl:result-document. [ERR XTRE1500] It is a recoverable dynamic error for a stylesheet to write to an external resource and read from the same resource during a single transformation, whether or not the same URI is used to access the resource in both cases. Example 3 --------- copy $doc := doc('update.xml') modify (insert node <node /> into $doc/nodes, fn:put($doc, "update.xml")) return (count($doc/nodes/node), count(doc('update.xml')/nodes/node)) Because 'doc' is stable the two calls to doc must return the same result, even though an update has occurred. Example 4 --------- copy $doc := <a /> modify (fn:put($doc, "update.xml")) return doc('update.xml') Does doc('update.xml') see the newly created resource, or the original resource (if we assume one was available)? 78024 1 christian.gruen 2012-11-08 00:04:25 +0000 Has there been any more discussion on this issue? I would even suggest to completely disallow fn:put() functions inside transform expressions in order to reduce the chance of indeterministic, implementation-dependent behavior. For example, in the following example.. copy $a := <a/> modify fn:put($a, "1") return (), copy $b := <b/> modify fn:put($b, "2") return () we will have no guarantee if $a or $b will be found in the final result. 78033 2 tim 2012-11-08 07:17:41 +0000 The WG hasn't discussed bugs against XQuery Update 1.0 for quite some time due to a focus on XQuery 3.0. 81411 3 jonathan.robie 2013-01-15 17:41:21 +0000 The Working Group has decided that it is an error if the modify clause of a transform expression produces a upd:put primitive. 113076 4 tim 2014-10-14 09:18:52 +0000 I'm reopening, as I'm unable to find the agreed change in the XQuery Update 3.0 editor's draft. 113082 5 john.snelson 2014-10-14 09:36:16 +0000 I'm closing this bug again, as the decision is recorded in changes.txt and will be made in the course of time.