Unable to Access #attributes in XML Node - php

Question

I am trying to access the 'field' element in the 'criteria' node in the following XML:
<?xml version="1.0" encoding="utf-8"?>
<result>
<product>
<data>
<field>spr_tech1</field>
<value>S7</value>
<criteria field="xfield_3">
<criteria_list>Green</criteria_list>
<criteria_list>Beige</criteria_list>
</criteria>
</data>
<data>
<field>spr_tech1</field>
<value>S1</value>
<criteria field="xfield_3">
<criteria_list>Red</criteria_list>
<criteria_list>Blue</criteria_list>
<criteria_list>Yellow</criteria_list>
</criteria>
</data>
<data>
<field>spr_tech1</field>
<value>S7</value>
<criteria field="xfield_3">
<criteria_list>Green</criteria_list>
</criteria>
<criteria field="tech_rt2">
<criteria_list>Transistor</criteria_list>
</criteria>
</data>
</product>
</result>
The code below results in the following error:
Fatal error: Call to a member function attributes() on a non-object
function parseXmlFile($filename)
{
$xml = file_get_contents($filename);
$obj = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);
$array = json_decode(json_encode($obj), true); // Convert to array}
return $array;
}
$xform = parseXmlFile('transformations.xml');
foreach ($xform['product']['data'] as $data)
{
echo (string)$data['field'] . '<br>';
echo (string)$data['value'] . '<br>';
foreach($data['criteria']->attributes() as $att => $val)
{ echo $att . ' = ' . $val . '<br>'; }
echo $data['criteria']->attributes()->{'field'} . '<br>';
foreach($data['criteria']['criteria_list'] as $att => $val)
{ echo $att . ' = ' . $val . '<br>'; }
echo "-----------------------------------<br>";
}
print "<pre>";
print_r($xform);
print "</pre>";
I've tried a couple methods as you can see in the code, but neither are working for me.
Any help is appreciated!

Answer 1

It seems the problem is when you load the file.
I tried it with file_get_contents() See below
$xml_content = file_get_contents('path to your XML file');
$xform = simplexml_load_string($xml_content);
foreach ($xform['product']['data'] as $data)
{
echo (string)$data['field'] . '<br>';
echo (string)$data['value'] . '<br>';
foreach($data['criteria']->attributes() as $att => $val)
{ echo $att . ' = ' . $val . '<br>'; }
echo $data['criteria']->attributes()->{'field'} . '<br>';
foreach($data['criteria']['criteria_list'] as $att => $val)
{ echo $att . ' = ' . $val . '<br>'; }
echo "-----------------------------------<br>";
}
print "<pre>";
print_r($xform);
print "</pre>";

Answer 2

Your parseXmlFile function can be replaced completely with the built-in simplexml_load_file():
it loads the contents with file_get_contents first; simplexml_load_file vs simplexml_load_string will do this for you
it forces the LIBXML_NO_CDATA option, which is almost certainly not something you need; to get the text contents of a SimpleXML object - including CDATA - you use (string)$node
it converts the incredibly useful SimpleXML object into an array that will be missing half of the data and much worse to work with
To understand SimpleXML, look at the examples in the manual. Elements are accessed with ->name and attributes with ['name'].
So:
$xform = simplexml_load_file('transformations.xml');
foreach ($xform->product->data as $data)
{
echo (string)$data->field . '<br>';
echo (string)$data->value . '<br>';
foreach($data->criteria->attributes() as $att => $val)
{ echo $att . ' = ' . $val . '<br>'; }
echo $data->criteria['field'] . '<br>';
foreach($data->criteria->criteria_list as $number => $node)
{ echo $number . ' = ' . (string)$node . '<br>'; }
echo "-----------------------------------<br>";
}