php xpath get node where attribute equals

Question

I have an xml how can I get the node in levelone that has an attribute called myatt whose value is a and then access it's myval. I tried referencing other posts to make it work but it doesn't seem to work what's wrong with my xpath

$this->myXmlObj->xpath("//levelone[myfield[attributes/myatt='a]]]"));

<myxml>
  <levelone>
      <myfield myatt="a" myval="aa" />
      <myfield myatt="b" myval="bb" />

  </levelone>  
  <leveltwo>
      <myfield myatt="c" myval="dd" />
      <myfield myatt="c" myval="dd" />
  </leveltwo>
</myxml>

edit 1

array
  0 => 
    object(SimpleXMLElement)[41]
      public '@attributes' => 
        array
          'myval' => string 'a' (length=40)

edit 2

    $myVar = $this->myXmlObj->xpath("//levelone/myfield[@myatt='a']");
    $myOutput = ((string)$myVar[0]->attributes()->myVal;

skabbes · Accepted Answer · 2011-04-07 21:58:38Z

9

Attributes in XPATH are referenced with @attr syntax. So, you could retrieve aa with the following xpath

//levelone/myfield[@myatt='a']/@myval

Which means, grab all myfield elements that have attribute myatt equal to 'a'. Then, from those, select the value of their myval attributes. Note that this could be multiple results.

A handy place to test XPATH expressions is at http://chris.photobooks.com/xml/default.htm.

answered Apr 7, 2011 at 21:58

skabbes

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4 Comments

user391986 Over a year ago

skabbes thanks so much that works for matching the node but i'm not getting the value as a string i'm getting a structure still (see edit 1)

salathe Over a year ago

@user391986, SimpleXML will only return elements from XPath queries, regardless of whether you ask for an attribute, string, number, etc. in the query.

user391986 Over a year ago

I see thanks so should I do like in edit2 or is there a better way to extract the value?

skabbes Over a year ago

I assume you're using DOMXPath->query, in which case you'll need to pull the attribute out with $xpathResult->nodeValue. You could also use DOMXPath->evaluate instead.

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