Element	Rules	Description
type	Mandatory	xpatheval
operand	Mandatory	the resource to be tested
operator	Mandatory	a canonical XPath
target	Mandatory Fragment OK	the target resource

The xpatheval accessor is used to perform a boolean test of an xpath expression on the operand. The operator contains a canonical XPath expression to be evaluated on the operand. xpatheval is often used for controlling process flow.

The truth of an XPath expression can include the document tree matches an xpath location, the value of a location matches a given value or an XPath function matches some value, or a combination of all of these. More information is avaliable here

xpatheval returns a canonical boolean document: t true, or f false

Example

Test if an Attribute has a given value

<idoc>
 <instr>
 <type>xpatheval</type>
 <operand>
 <a>
 
 </a>
 </operand>
 <operator>
 <xpath>//b[@name='foo']</xpath>
 </operator>
 <target>this:response</target>
 </instr>
</idoc>

An example of using xpatheval to test if the operand document has an element with an attribute name with value 'foo'. In this example the xpatheval returns true in the form of a canonical boolean document t

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