# 22. Virtuoso Functions Guide - xml_namespace_scope

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XPATH & XQUERY
Functions Index

## xml_namespace_scope

Returns a vector of all namespace declarations in all ancestors of the given XML entity.
vector xml_namespace_scope (in ent XML Entity, in use_default_ns integer);
Description

The function returns a vector of even length that consits of all declared namespace prefixes and namespace URIs from the ent and all its ancestors. This information is needed for processing XML documents that contains a mix of data and XPath expressions, such as BPEL documents.

Parameters
ent – The entity to process.
use_default_ns – Flags if the resulting array should contain declarations of default namespace. If it is zero then only declarations of namespace prefixes are listed; if non-zero then all declarations are listed.
Return Types

The funtion returns a vector of even length that contains narrow strings in UTF-8 encoding.

Examples
Adding namespace declarations to the XPath expression

The function gets an entity whose string-value is an XPATH expression and returns the text of expression with all namespace declarations that are in scope. The resulting expression is context-independent. This is useful for BPEL-like applications and for extracting XPATH expressions from XML Schema documents.

    create procedure xpath_add_namespace_scope (in ent any, in use_default_ns integer)
    {
      declare _expn varchar;
      declare _ses any;
      declare _scope any;
      declare _ctr any;
      _expn := charset_recode (xpath_eval ('string(.)', ent), '_WIDE_', 'UTF-8');
      _scope := xml_namespace_scope (ent, use_default_ns);
      _ctr := length (_scope);
      if (_ctr = 0)
        return _expn;
      _ses := string_output ();
      http ('[', _ses);
      while (_ctr > 0)
        {
          if (_scope[_ctr-2] = '')
            http (sprintf (' xmlns="%s"', _scope[_ctr-1]), _ses);
          else
            http (sprintf (' xmlns:%s="%s"', _scope[_ctr-2], _scope[_ctr-1]), _ses);
          _ctr := _ctr - 2;
        }
      http (' ] ', _ses);
      http (_expn, _ses);
      return string_output_string (_ses);
    }

    select xpath_add_namespace_scope (
      xquery_eval (
    'declare namespace xsd="http://www.w3.org/2001/XMLSchema";
    //xsd:keyref[@name="ISBNnumber"]/xsd:field/@xpath',
        xtree_doc (
    '<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            targetNamespace="http://www.publishing.org"
            xmlns="http://www.publishing.org">
      <xsd:element name="Book"  minOccurs="1" maxOccurs="unbounded">
        <xsd:keyref name="ISBNnumber" refer="BookDB_ISBN">
          <xsd:selector xpath="."/>
          <xsd:field xpath="ISBN"/>
        </xsd:keyref>
      </xsd:element>
      <!-- The rest of the XML Schema file is skipped -->
    </xsd:schema>')),
      1 );

    callret
    VARCHAR
    _______________________________________________________________________________

    [ xmlns="http://www.publishing.org" xmlns:xsd="http://www.w3.org/2001/XMLSchema" ] ISBN

See Also

xpath_eval