xml reader opens the file but still gives the 'Load Data before trying to read' error

Question

I have this weird error I don't really know how is this possible. The xmlreader reads the file, but when i am trying to iterate it, it still gives me the error "Message: XMLReader::read(): Load Data before trying to read".

Here is my code:

$what = 'title';
    $reader = new XMLReader;

    if (!$reader->open(base_url().'resources/thexml.xml'))
    {
        die("Failed to open");
    }
    else 
    {
        echo 'success!';
    }


    while($reader->read())
    {
        if ($reader->nodeType == XMLReader::ELEMENT && $reader->name == 'item')
        {
            $exp = $reader->expand();
            if ($exp->nodeName == $what)
                echo "<b>" . $exp->nodeName . " : </b>" . $exp->nodeValue . "<br />";

        }

        $reader->close();
    }

And this is the output:

success! A PHP Error was encountered

Severity: Warning

Message: XMLReader::read(): Load Data before trying to read

Filename: controllers/welcome.php

Line Number: 102

The success shows it reads the file but still gives me the error that I need to open first. Line number 102 is "while($reader->read())" line. Please help

Answer 1

I found out the problem: You need to move the $reader->close(); statement outside of the loop. Otherwise the xml document gets closed after the first loop and the subsequent read operations fails.

The read loop should look like this:

while($reader->read())
{
    if ($reader->nodeType == XMLReader::ELEMENT && $reader->name == 'item')
    {
        $exp = $reader->expand();
        if ($exp->nodeName == $what)
            echo "<b>" . $exp->nodeName . " : </b>" . $exp->nodeValue . "<br />";

    }
}

// Close the document after(!) the loop
$reader->close();

Having this your code works properly.

---

However, using XMLReader doesn't seem the appropriate solution here. This because it requires to loop over all(!) tags in the input xml while you are only interested in the <item> nodes. I would use DOMDocument together with XPath here:

// Create an load the DOM document
$doc = new DOMDocument();
$doc->load('thexml.xml');

// Create an XPath selector
$selector = new DOMXPath($doc);

// Get all <title> nodes inside <item> nodes
foreach($selector->query('//item/title') as $item) {
    echo '<b>Title: ' . $item->nodeValue . '</br>';
}