Using an attribute value as part of an XPath query

[rxjones]

I'm working with an XML file describing a database's metadata (i.e., just the tables and other structural elements and their relationships, not any data itself). It was generated by a commercial application and I do not have access to the DTD.

Is there a way given the following XML tree to get the Ref value "o16" and use it to find the o:Column element with an Id of the same value? I can do it when I specifically enter a static value in the XPath (ex. //o:Column[attribute::Id="o16"]), but need to be able to loop through any existing references using xsl:for-each (ex. //o:Column[attribute::Ref="X"] where X is the current value of Ref in the xsl:for-each). Ultimately I want to get //o:Column[attribute::Ref="X"]/a:Name

Code: Select all

<model>

   <o:RootObject>

      <c:Tables>

         <o:Table>

            <a:Name>

            <c:Columns>

               <o:Column Id="o16">

                  <a:Name>

            <c:Indexes>

               <o:Index>

                  <a:Name>

                  <c:IndexColumns>

                     <o:IndexColumn>

                        <c:Column>

                           <o:Column Ref="o16">

Thanks for the help

Roland

[sorin_ristache]

Hello,

A solution is to use a key to map the Ref attribute to the o:Column element with an Id attribute of the same value. The following example just output the string value of the a:Name element. Of course you have to replace o-namespace, c-namespace and a-namespace with your values.

Code: Select all

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0" xmlns:o="o-namespace" xmlns:c="c-namespace" xmlns:a="a-namespace">

    <xsl:key name="columnId" match="o:Column" use="@Id"/>

    

    <xsl:template match="/">

        <xsl:for-each select="//o:Column[@Ref]">

           <!-- Here access the a:Name child of the o:Column element with the Id = @Ref. -->

           <!--  For that use: key('columnId', @Ref)/a:Name  -->

            <xsl:value-of select="key('columnId', @Ref)/a:Name"/>

        </xsl:for-each>

    </xsl:template>

</xsl:stylesheet>

Regards,
Sorin