Question

I am attempting to parse an xml file with attributes, and keep getting an empty array. Here is a sample of the xml, which is parsed as a simplexml_load_string:

     <NumberOfOfferListings>
    <OfferListingCount condition="Any">61</OfferListingCount>
    <OfferListingCount condition="Used">45</OfferListingCount>
    <OfferListingCount condition="New">16</OfferListingCount>
  </NumberOfOfferListings>

Here is the php code that I am using

$priceComp_xml = amazonCompPrice_xml($asin);
$compPricing = $priceComp_xml->xpath('OfferListingCount[@condition="Any"]'); 

amazonCompPrice($asin) is the parsed xml file based on the ASIN value.

I need to extract just:

<OfferListingCount condition="Any">61</OfferListingCount>

I have looked at many examples on here to get to this point, and it looks like what I have is correct, just returns an empty array when I use either print_r($compPricing) or var_dump.
How do I fix this to get the information that I need??
I can upload any more snippets of code that will help resolve this issue.

Answer 1

There are (at least) two separate issues at play here.

The XPath

Your XPath, OfferListingCount[@condition="Any"], will only return matching <OfferListingCount> elements which are children of the element held in $priceComp_xml. It will not match descendant elements which are grand-children, or further down the tree.

So, it needs to be amended to match the <OfferListingCount> element(s). A quick fix usually to employ the shorthand // (short for /descendant-or-self::node()/), like //OfferListingCount[@condition="Any"].

Namespaces

Your question did not mention this, but some digging uncovered that the XML document probably has a default namespace applied to it. This can be recognised by looking at the document element for xmlns="…". When using XPath, this namespace needs to be registered and used when querying.

$priceComp_xml->registerXPathNamespace('products', 'http://mws.amazonservices.com/schema/Products/2011-10-01');
$compPricing = $priceComp_xml->xpath('//products:OfferListingCount[@condition="Any"]');

Finally, remember that SimpleXMLElement::xpath() returns an array, so your matching <offerListingCount> element will be available as $compPricing[0].

$count = (int) $compPricing[0];