sep 22 2019, 5:04am feb 8, 2022
The DOMDocument class is good for reading small XML file but for large / huge XML, code may stall and give you no error at all. For large XML, you should use XMLReader instead to preserve your server memory usage.
A huge example of XML was downloaded from this page at Karaoke Version affiliation program and it generally has following structure:
<artists> <artist id="2000"> <name>The Solids</name> <name_sorted>Solids, The</name_sorted> <url>http://www.karaoke-version.com/mp3-backingtrack/the-solids/</url> <rank>5866</rank> <songs> <song id="5022"> <name>Hey Beautiful</name> <url>http://www.karaoke-version.com/mp3-backingtrack/the-solids/hey-beautiful.html</url> <rank>24467</rank> <preview>http://www.karaoke-version.com/preview/57278/</preview> ...
If we somehow need to save that into our database then we may format a data row / line i.e: artist's name, artist's song name and the link for previewing the audio. Example:
The Solids, Hey Beautiful, http://www.karaoke-version.com/preview/57278/ ...
<?php
$t = time();
$m = memory_get_usage();
const XML_FILENAME = 'karaokeversion_catalog_en_GBP.xml';
$liner = new XMLReader();
if($liner->open(XML_FILENAME)){
$artistCount = 0; //number of artists
$songCount = 0; //number of songs of all artists
while($liner->read()){
if($liner->nodeType === XMLReader::ELEMENT && $liner->name === 'artist'){
//convert current line into an XML node
$node = $liner->expand();
//for each artist node found, assume unknown artist name, initialize it
$artistName = '';
//walk through this artist node's child nodes to find artist name and songs
for($j = 0; $j < $node->childNodes->length; $j++){
$nodeChild = $node->childNodes->item($j);
if($nodeChild->nodeType === XML_ELEMENT_NODE && $nodeChild->nodeName === 'name')
$artistName = $nodeChild->nodeValue;
elseif($nodeChild->nodeName === 'songs'){
//walk through this songs node's child nodes
for($k = 0; $k < $nodeChild->childNodes->length; $k++){
$nodeGrandChild = $nodeChild->childNodes->item($k);
if($nodeGrandChild->nodeType === XML_ELEMENT_NODE && $nodeGrandChild->nodeName === 'song'){
//for each song node found, assume unknown song details, initialize them
$songName = '';
$songPreview = '';
//walk through this song node's child nodes
for($l = 0; $l < $nodeGrandChild->childNodes->length; $l++){
$nodeGrandGrandChild = $nodeGrandChild->childNodes->item($l);
if($nodeGrandGrandChild->nodeType === XML_ELEMENT_NODE){
if($nodeGrandGrandChild->nodeName === 'name')
$songName = $nodeGrandGrandChild->nodeValue;
elseif($nodeGrandGrandChild->nodeName === 'preview')
$songPreview = $nodeGrandGrandChild->nodeValue;
}
}
//add validation first here then format a new entry line to be stored somewhere
if(!empty($artistName) && !empty($songName) && filter_var($songPreview, FILTER_VALIDATE_URL)){
echo "$artistName, $songName, $songPreview\n";
$songCount++;
}
}
}
}
}
$artistCount++;
}
}//end while
$liner->close();
//report
$t = time() - $t;
$m = memory_get_usage() - $m;
echo "\ntime spent: $t seconds.",
"\nmemory usage: $m bytes.",
"\nartist count: $artistCount.",
"\nsong count: $songCount.";
}
else //if $liner->open fails
echo 'error: can not open xml file.';
?>
Click on following link to test: huge-xml-read (on a sister site).
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