XPATH - get single value returned instead of array php

Question

I am using Xpath in PHP - I know that my query will return either 0 or 1 results.

If 1 result is returned I do not want it as an array - which is what is returned ri

Answer 1

If 1 result is returned I dont want it as an array - which is what is returned. I simply want the value without having to access the [0] element of the result and cast to a string.

That is possible with XPath's string function

A node-set is converted to a string by returning the string-value of the node in the node-set that is first in document order. If the node-set is empty, an empty string is returned.

and DOMXPath's evaluate method:

Returns a typed result if possible or a DOMNodeList containing all nodes matching the given XPath expression.

Example:

$dom = new DOMDocument;
$dom->loadXML('');
$xp = new DOMXPath($dom);
var_dump($xp->evaluate('string(/root/@foo)')); // string(3) "bar"

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If there was a built in xpath way of grabbing the first and only the first node value then that would be much more preferable over writing a function to do it

You can use the position function:

The position function returns a number equal to the context position from the expression evaluation context.

Example:

$dom = new DOMDocument;
$dom->loadXML('');
$xp = new DOMXPath($dom);
var_dump($xp->evaluate('string(/root/foo[position() = 1]/@xml:id)')); // string(2) "f1"

or the abbreviated syntax

$dom = new DOMDocument;
$dom->loadXML('');
$xp = new DOMXPath($dom);
var_dump($xp->evaluate('string(/root/foo[1]/@xml:id)')); // string(2) "f1"

Note that when querying for descendants with // using the position function might yield multiple result due to the way the expression is evaluated.