Name
processXQuery — Calls an XQuery module from XPath expression, e.g. from some XSLT or BPEL code.
Synopsis
any processXQuery ( |
module_uri string , |
| context entity , | |
| index integer , | |
| param1_name string , | |
| param1_value any ... , | |
| paramN_name string, | |
paramN_value any); |
Description
This function takes a URI of an XQuery module and an XML entity
and calls the module with the entity as a context. Depending on
value of index parameter,
either the result of the module is returned 'as is' or the sequence
of results is returned.
Parameters can be passed to the module by specifying additional
arguments to processXQuery() . The
names of parameters should appear in argument list without the
leading '$' sign. Unlike xquery_eval()
function, parameter can not be ignored depending on the type of its
value. If the same name appears more than once in the vector, the
last name/value pair is used and all preceding pairs with this name
are silently ignored. Obviously, names should be strings that are
valid XPath variable names.
The XQuery standard does not offer a way of calling of a module
from other XQuery expression. The reason is that there's no need
for such calling if the code is designed properly. If an expression
is re-used in various places then it should be turned into a
function and placed into an XQuery library module; one should
import the module and call the function instead of calling a
non-library module. It is possible to use processXQuery() in XQuery expressions but it is
much better to use library modules instead, and to use processXQuery() only for tricks in XPATH
expressions.
For compatibility, the processXQuery() function can also be called as
http://schemas.oracle.com/xpath/extension:processXQuery()
.
Parameters
module_uri
URI pointing to the location of an XQuery module. It can be absolute or relative. A relative module_uri should be resolved before use, this requires base URI information. Base URI can be declared explicitly by "__base_uri" parameter in XPATH or "declare base-uri" setter in XQuery. If not declared but the expression is a part of some stylesheet or XQuery module then the URI of module is used as a base URI. A run-time error is signalled if the URI is relative and the expression does not contain explicit declaration and the expression is neither in a stylesheet nor in a module.
index
Result index. If omitted a value of 1 is assumed, meaning only the first result is returned. If a value of 0 is supplied then a (flatten) sequence of all results is returned. (Note that if a non-zero value is specified then the returned value still can be a sequence).
context
XML entity that is the context node of module call. If the
function is called with only one argument then the current context
node of the processXQuery() call is
used as a context of module call. (In any case, context size and
context position of module call are always set to 1 and not
inherited from call of processXQuery() .)
paramI_name
Name of parameter to be passed to the XSLT engine for use in the transformation.
paramI_value
Value of parameter with name specified by paramI_name .
Return Types
The type of return value depends on type of value returned by module.
Examples
Example24.611.Call of XQuery in XSLT
Sample templates put the result of the call of module "mymodule.xq" for context node into the resulting document. This assumes that both the stylesheet and XQuery module "mymodule.xq" reside in the same directory so relative a URI "mymodule.xq" can be resolved using the URI of the stylesheet as base URI.
<xsl:template match="myelement">
<xsl:copy-of select="processXQuery('mymodule.xq')"/>
</xsl:template>
This is equivalent with the following template:
<xsl:template match="myelement">
<xsl:copy-of select="processXQuery('mymodule.xq', current(), 1)"/>
</xsl:template>