PHP - Manual: XMLReader::read

2024-11-14

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XMLReader::read

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

XMLReader::read — Move to next node in document

说明

public XMLReader::read(): bool

Moves cursor to the next node in the document.

参数

此函数没有参数。

返回值

成功时返回 true，或者在失败时返回 false。

参见

XMLReader::moveToElement() - Position cursor on the parent Element of current Attribute
XMLReader::moveToAttribute() - Move cursor to a named attribute
XMLReader::next() - Move cursor to next node skipping all subtrees

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User Contributed Notes 6 notes

down

jirka at kosek dot cz ¶

16 years ago


libxml2 contains much more useful method readString() that will read and return whole text content of element. You can call it after receiving start tag (XMLReader::ELEMENT). You can use this PHP code to emulate this method until PHP will directly call underlying libxml2 implementation.

<?php
class XMLReader2 extends XMLReader
{
  function readString()
  {
        $depth = 1;
        $text = "";

        while ($this->read() && $depth != 0)
        {
            if (in_array($this->nodeType, array(XMLReader::TEXT, XMLReader::CDATA, XMLReader::WHITESPACE, XMLReader::SIGNIFICANT_WHITESPACE)))
                $text .= $this->value;
            if ($this->nodeType == XMLReader::ELEMENT) $depth++;
            if ($this->nodeType == XMLReader::END_ELEMENT) $depth--;
        }
        return $text;
    }
}
?>

Just use XMLReader2 instead of XMLReader.

down

Nate ¶

10 years ago


It is interesting to note that this function will stop on closing tags as well.  I have an XML document similar to the following:


<root>

  <columns>

    <column>columnX</column>

    <column>columnY</column>

  </columns>

  <table>

    <row>

      <columnX>38</columnX>

      <columnY>50</columnY>

    </row>

    <row>

      <columnX>82</columnY>

      <columnY>28</columnY>

    </row>

    ...

  </table>

</root>


I need to parse the <columns> object to know what attributes to check for from each <row> node.  Therefore I was doing the following:


<?php

while ($xml->read()) {

  if ($xml->name === 'column') {

   //parse column node to into $columns array

  }

  elseif ($xml->name === 'row') {

    //parse row node, using constructed $columns array

  }

}

?>



This kind of worked in that I ended up with an array of all the data I wanted, but the array I constructed was twice as large as I expected and every other entry was empty.  Took me a while to debug, but finally figured out that checking <?php $xml->name === 'row' ?> matches both <row> and </row>, so the check should really be something more like:


<?php


if ($xml->name === 'row' && $xml->nodeType == XMLReader::ELEMENT) {

  // parse row node

}


?>



I would have liked to use the next() function instead, but as I needed to parse 2 different subtrees, I couldn't figure out how to find all the columns, reset the pointer, and then find all the rows.

down

peter at 3xe dot co dot uk ¶

5 years ago


Another approach to the 'also reads closing tags' gotcha:

<?php
$reader = new XMLReader();
$reader->open('users.xml');

while ($reader->read()) {
  if ($reader->nodeType == XMLReader::END_ELEMENT) {
    continue; //skips the rest of the code in this iteration
  }
  //do something with desired node type
  if($reader->name == 'user') {
    //...
  }
}
?>

down

ecziegler at gmail ¶

8 years ago


If like myself you have been turning the interwebz upside down looking for a solution for this issue:
PHP Warning:  XMLReader::read(): /tmp/xml_feed.xml:4183934: parser error : Input is not proper UTF-8, indicate encoding !

For some reason, this warning breaks the execution - is it a fatal error in disguise?

After days of frustration I found it!!!!
tidy -xml -o output.xml -utf8 -f error.log input.xml

You can invoque tidy using exec, It takes several seconds to convert a 250Mb feed, but it worthy the time.

In my case the issue was with latin1 charset, and for some reason I had to pass the xml through tidy 2 times - first time around creates new errors, second time it fixes everything.

I know invalid xml should be fixed by xml creators, but it works differently in the real world.

down

-3

Anonymous ¶

7 years ago


> I would have liked to use the next() function instead, but as I needed to parse 2 different subtrees, I couldn't figure out how to find all the columns, reset the pointer, and then find all the rows. 

I just use:

$reader->close();
$reader->open($url);

to reset the pointer.

down

-12

andy at siliconrockstar dot com ¶

11 years ago


A very simple way to avoid typing $reader->read() multiple times when you want to skip some nodes:


<?php

class smartXMLReader extends XMLReader {

    public function readTimes($count) {

        $i = 0;

        while($i < $count){

            $this->read();

            $i++;

        }

    }

}

?>



Using this smartXMLReader, 


<?php

$reader->readTimes(3);

?>



is equivalent to 


<?php

$reader->read();

$reader->read();

$reader->read();

?>



Makes getting around in your XML document a bit easier :)

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官方地址：https://www.php.net/manual/en/xmlreader.read.php

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XMLReader::read

说明

参数

返回值

参见

User Contributed Notes 6 notes