XSLT selecting one of two nodes with same name based on attribute value

Question

I have some XML Markup that looks like the following:

<pet type="dog" id="76">
</pet>
<pet type="cat" id="79">
</pet>

In this particular case, using XSLT - what's the most optimal way to create a variable to retrieve the cat and dog ids? The order is never the same so /pet[1] wouldn't work. It would have to be something such as:

<xsl:variable name="cat_id"><xsl:value-of select="...."/></xsl:variable>
<xsl:variable name="dog_id"><xsl:value-of select="...."/></xsl:variable>

Answer 1

Well <xsl:variable name="cat_id" select="//pet[@type = 'cat']/@id"/> is the direct way, if you want efficient access define a key

<xsl:key name="pet-by-type" match="pet" use="@type"/>

and then use

<xsl:variable name="cat_id" select="key('pet-by-type', 'cat')/@id"/>

.

Answer 2

I would try something like this

<xsl:variable name="cat_id"><xsl:value-of select="pet[@type='cat']/@id "/ ></xsl:variable>

But it also depends on your actual position in input xml.