How to select the first element with a specific attribute using XPath

Use:

(/bookstore/book[@location='US'])[1]

This will first get the book elements with the location attribute equal to 'US'. Then it will select the first node from that set. Note the use of parentheses, which are required by some implementations.

Note, this is not the same as /bookstore/book[1][@location='US'] unless the first element also happens to have that location attribute.


The easiest way to find first english book node (in the whole document), taking under consideration more complicated structered xml file, like:

<bookstore>
 <category>
  <book location="US">A1</book>
  <book location="FIN">A2</book>
 </category>
 <category>
  <book location="FIN">B1</book>
  <book location="US">B2</book>
 </category>
</bookstore>

is xpath expression: 

/descendant::book[@location='US'][1]


As an explanation to Jonathan Fingland's answer:

  • multiple conditions in the same predicate ([position()=1 and @location='US']) must be true as a whole
  • multiple conditions in consecutive predicates ([position()=1][@location='US']) must be true one after another
  • this implies that [position()=1][@location='US'] != [@location='US'][position()=1]
    while [position()=1 and @location='US'] == [@location='US' and position()=1]
  • hint: a lone [position()=1] can be abbreviated to [1]

You can build complex expressions in predicates with the Boolean operators "and" and "or", and with the Boolean XPath functions not(), true() and false(). Plus you can wrap sub-expressions in parentheses.


/bookstore/book[@location='US'][1] works only with simple structure.

Add a bit more structure and things break.

With-

<bookstore>
 <category>
  <book location="US">A1</book>
  <book location="FIN">A2</book>
 </category>
 <category>
  <book location="FIN">B1</book>
  <book location="US">B2</book>
 </category>
</bookstore>

/bookstore/category/book[@location='US'][1] yields

<book location="US">A1</book>
<book location="US">B2</book>

not "the first node that matches a more complicated condition". /bookstore/category/book[@location='US'][2] returns nothing.

With parentheses you can get the result the original question was for:

(/bookstore/category/book[@location='US'])[1] gives

<book location="US">A1</book>

and (/bookstore/category/book[@location='US'])[2] works as expected.

Tags:

Xpath

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