XPath function
string()
Converts anything to a string — and for a node-set, takes only the first node in document order.
string() converts its argument using XPath's conversion rules: a number becomes its decimal form, a boolean becomes 'true' or 'false', and a node-set becomes the string-value of its first node in document order.
That last rule is the one that surprises people. string(//line/@sku) is not all three SKUs — it is the first, silently.
- Syntax
string(object?) → string- Returns
- string
- Kind
- Function
- Version
- XPath 1.0 (libxml2)
Worked examples
Each result below is what the evaluator returned, asserted on every test run. An empty result means an empty node-set — which is an answer, not an error.
What catches people out
- On a node-set it uses the first node only. To get every value, select the node-set itself rather than converting it.
- string() of an empty node-set is the empty string, not an error.
- The string-value of an element is the concatenation of all descendant text, indentation included — see normalize-space().
The sample documents
Every example on this page runs against this document. The sitemap one is namespaced on purpose — almost every real XML document is, and that changes which expressions match.
<?xml version="1.0" encoding="UTF-8"?>
<order id="A-1001" tier="gold">
<customer country="NO">Ada Lovelace</customer>
<lines>
<line sku="WIDGET-1" qty="2"><price>14.50</price></line>
<line sku="WIDGET-2" qty="1"><price>39.00</price></line>
<line sku="GIFT-WRAP" qty="1"><price>0.00</price></line>
</lines>
<note> Deliver after 09:00 </note>
</order>Related
- concat()Joins two or more strings. There is no + for strings in XPath.
- number()Converts to a number, producing NaN rather than an error when it cannot — which is how bad data passes silently.
- normalize-space()Trims leading and trailing whitespace and collapses internal runs to single spaces — the fix for text that looks equal and is not.
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