PHP - very basic XMLReader

Question

Because I will be parsing a very large XML file, I am trying to use XMLReader to retrieve the XML data, and use simpleXML to display. I have never used XMLreader, so I am simply trying to get a basic feel for using XMLReader. I want to display all the name and price values in the XML file, and I cannot get this code to display anything. Am I missing something?

Here is the XMLReader/simpleXML code:

$z = new XMLReader;
$z->open('products.xml');
$doc = new DOMDocument;

while ($z->read() && $z->name === 'product') {
$node = simplexml_import_dom($doc->importNode($z->expand(), true));

var_dump($node->name);
$z->next('product');
}

Here is the XML file, named products.xml:

<products>

<product category="Desktop">
<name> Desktop 1 (d)</name>
<price>499.99</price>
</product>

<product category="Tablet">
<name>Tablet 1 (t)</name>
<price>1099.99</price>
</product>

</products>

ThW · Accepted Answer · 2015-04-07 11:51:05Z

1

Your loop condition is broken. You loop if you get an element AND that elements name is "product". The document element is "products", so the loop condition is never TRUE.

You have to be aware that read() and next() are moving the internal cursor. If it is on a <product> node, read() will move it to the first child of that node.

$reader = new XMLReader;
$reader->open($file);
$dom   = new DOMDocument;
$xpath = new DOMXpath($dom);

// look for the first product element
while ($reader->read() && $reader->localName !== 'product') {
  continue;
}

// while you have an product element
while ($reader->localName === 'product') {
  $node = $reader->expand($dom);
  var_dump(
    $xpath->evaluate('string(@category)', $node),
    $xpath->evaluate('string(name)', $node),
    $xpath->evaluate('number(price)', $node)
  );
  // move to the next product sibling
  $reader->next('product');
}

Output:

string(7) "Desktop"
string(14) " Desktop 1 (d)"
float(499.99)
string(6) "Tablet"
string(12) "Tablet 1 (t)"
float(1099.99)

edited Apr 7, 2015 at 11:51

answered Apr 15, 2014 at 9:07

ThW

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3 Comments

Dean Olsen Over a year ago

Thanks! You steered me in the right direction - enough to where I can hopefully incorporate simpleXML into displaying the results after XMLReader parses the XML.

ThW Over a year ago

I prefer using DOM+XPath. SimpleXML is to much work.

Dean Olsen Over a year ago

In working with this, I believe you are correct about simpleXML being too much work. I'm relatively new to programming, so I appreciate your help!

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