SimpleXML get element content based on attribute value

Question

I'm trying to access the content of an element based on the value of an attribute. With PHP SimpleXML. I've got the following XML setup:

<DocSum> 
    <Id>21242919</Id> 
    <Item Name="Author" Type="String">Nguyen T</Item>
    <Item Name="Title" Type="String">[Hemoptysis and spontaneous rupture of a primary renal angiosarcoma: a case report.]</Item>
</DocSum>
<DocSum> 
    <Id>21242919</Id> 
    <Item Name="Author" Type="String">Oliveira GC</Item>
    <Item Name="Title" Type="String">Disclosing ambiguous gene aliases by automatic literature profiling.</Item>
</DocSum>
<DocSum> 
    <Id>21242919</Id> 
    <Item Name="Author" Type="String">Vanderwall DE</Item>
    <Item Name="Title" Type="String">Metformin and digestive disorders.</Item>
</DocSum>

These are books. In this case I'm trying to get the title. What I have so far is this:

$xml = simplexml_load_file(url);
$docs = $xml->DocSum;
foreach($docs as $book){
        // Each book individual
}

Where the comment is I tried a lot of things.

Answer 1

This XPath query on the SimpleXML object will return all DocSum nodes that have an Item child with value "Author" in the Name attribute and value "Olivera GC" in the text node:

$nodes = $xml->xpath('//DocSum[Item[@Name="Author" and .="Oliveira GC"]]');
$book = $nodes[0];
print_r($book);