Question

I am trying to iterate over set of nodes given by xpath and set certain attribute for each node. However it works only for nodes withou content or with empty (whitespace) content. I have tried 2 approaches but with the same result (maybe they are both the same on some deeper level, dunno). The commented line is the second approach.

$temp = simplexml_load_string (
'<toolbox>
    <hammer/>
    <screwdriver>   </screwdriver>
    <knife>
        sharp
    </knife>
</toolbox>' );

echo "vanilla toolbox: ";
print_r($temp);

$nodes = $temp->xpath('//*[not(@id)]');

foreach($nodes as $obj) {
    $tempdom = dom_import_simplexml($obj);
    $tempdom->setAttributeNode(new DOMAttr('id', 5));
    //$obj->addAttribute('bagr', 5);
}

echo "processed toolbox: ";
print_r($temp);

This is output. Attribute id is missing in node knife.:

vanilla toolbox: SimpleXMLElement Object
(
[hammer] => SimpleXMLElement Object
    (
    )

[screwdriver] => SimpleXMLElement Object
    (
        [0] =>    
    )

[knife] => 
        sharp

)
processed toolbox: SimpleXMLElement Object
(
[@attributes] => Array
    (
        [id] => 5
    )

[hammer] => SimpleXMLElement Object
    (
        [@attributes] => Array
            (
                [id] => 5
            )

    )

[screwdriver] => SimpleXMLElement Object
    (
        [@attributes] => Array
            (
                [id] => 5
            )

        [0] =>    
    )

[knife] => 
        sharp

Answer 1

I’m unable to reproduce what you describe, the changed XML is:

<?xml version="1.0"?>
<toolbox id="5">
    <hammer id="5"/>
    <screwdriver id="5">   </screwdriver>
    <knife id="5">
        sharp
    </knife>
</toolbox>

Demo

It’s exactly your code, maybe you’re using a different LIBXML version? See the LIBXML_VERSION constant (codepad viper has 20626 (2.6.26)).

But probably it’s just only the print_r output for a SimpleXMLElement object.

It does not output the attributes for the last element, even on a brand new object, but it’s still possible to access the attribute. Demo.

You will see when you print_r($temp->knife['id']); that the attribute is set (as you can see in the earlier XML output).