Difference between revisions of "XQuery Module"
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|Evaluates {{Code|$query}} as XQuery expression at runtime and returns the resulting items.<br />Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings, the values can be arbitrary item sequences: | |Evaluates {{Code|$query}} as XQuery expression at runtime and returns the resulting items.<br />Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings, the values can be arbitrary item sequences: | ||
* variables specified as QNames will be directly interpreted as variable name. | * variables specified as QNames will be directly interpreted as variable name. | ||
| − | * variables specified as xs:string may be prefixed with a dollar sign. Namespace can be specified using the [http://www.jclark.com/xml/xmlns.htm Clark Notation]. If the specified string is empty, the value will be bound to the context item. | + | * variables specified as xs:string may be prefixed with a dollar sign. Namespace can be specified using the [http://www.jclark.com/xml/xmlns.htm Clark Notation]. |
| + | * If the specified string is empty, the value will be bound to the context item. | ||
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
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| | | | ||
* {{Code|xquery:eval("1+3")}} returns {{Code|4}}.<br /> | * {{Code|xquery:eval("1+3")}} returns {{Code|4}}.<br /> | ||
| + | * You can bind the context and e.g. operate on a certain database only:<br /> | ||
| + | <pre class='brush:xquery'> | ||
| + | xquery:eval("//country", map{ '' := db:open('factbook') }) | ||
| + | </pre> | ||
* The following expressions use strings as keys. All of them return 'XML':<br/> | * The following expressions use strings as keys. All of them return 'XML':<br/> | ||
<pre class='brush:xquery'> | <pre class='brush:xquery'> | ||
Revision as of 15:22, 8 March 2013
This XQuery Module contains functions to evaluate XQuery strings and modules at runtime.
Contents
Conventions
All functions in this module are assigned to the http://basex.org/modules/xquery namespace, which is statically bound to the xquery prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.
Functions
xquery:eval
| Signatures | xquery:eval($query as xs:string) as item()*xquery:eval($query as xs:string, $bindings as map(*)) as item()* |
| Summary | Evaluates $query as XQuery expression at runtime and returns the resulting items.Variables and context items can be declared via $bindings. The specified keys must be QNames or strings, the values can be arbitrary item sequences:
|
| Errors | BXXQ0001: the query contains updating expressions.
|
| Examples |
xquery:eval("//country", map{ '' := db:open('factbook') })
xquery:eval(".", map{ '' := 'XML' })
xquery:eval("$xml", map{ 'xml' := 'XML' }),
xquery:eval("$xml", map{ '$xml' := 'XML' }),
xquery:eval("declare namespace pref='URI'; $pref:xml", map{ '{URI}xml' := 'XML' }),
declare namespace pref = 'URI';
xquery:eval("$xml", map{ xs:QName('xml') := 'XML' })
xquery:eval("declare namespace pref='URI'; $pref:xml", map{ xs:QName('pref:xml') := 'XML' }),
|
xquery:invoke
| Signatures | xquery:invoke($uri as xs:string) as item()*xquery:invoke($expr as xs:string, $bindings as map(*)) as item()* |
| Summary | Opens $uri as file, evaluates it as XQuery expression at runtime, and returns the resulting items.The semantics of the $bindings parameter is the same as for xquery:eval.
|
| Errors | BXXQ0001: the query contains updating expressions.
|
xquery:type
| Signatures | xquery:type($expr as item()*) as item()*
|
| Summary | Similar to fn:trace($expr, $msg), but instead of a user-defined message, it emits the compile-time type and estimated result size of its argument.
|
Errors
| Code | Description |
|---|---|
BXXQ0001
|
A dynamically evaluated query must not contain any updating expressions. |
Changelog
This module was introduced with Version 7.3. Functions have been adopted from the obsolete Utility Module.
