Here's the XML code I'm working with:
<inventory>
<drink>
<lemonade supplier="mother" id="1">
<price>$2.50</price>
<amount>20</amount>
</lemonade>
<lemonade supplier="mike" id="4">
<price>$3.00</price>
<amount>20</amount>
</lemonade>
<pop supplier="store" id="2">
<price>$1.50</price>
<amount>10</amount>
</pop>
</drink>
</inventory>
Then I wrote a simple code to practice working with XPath:
<?php
$xmldoc = new DOMDocument();
$xmldoc->load('sample.xml');
$xpathvar = new Domxpath($xmldoc);
$queryResult = $xpathvar->query('//lemonade/price');
foreach($queryResult as $result) {
echo $result->textContent;
}
?>
That code is working well, outputting all the lemonade price values as expected. Now when i change the query string to select only the elements with an attribute set to a certain value, like
//lemonade[supplier="mother"]/price
or
//lemonade[id="1"]/price
it won't work, no output at all. What am i doing wrong?
Try this:
//lemonade[@id="1"]/price
or
//lemonade[@supplier="mother"]/price
Without the "@" it looks for child elements with that name instead of attributes.
This is only tangentially related, but when you use XPath on a document for which you know the structure, don't use "//some-element-name". It's very nice for a quick example, but when you hit a huge xml file with that query, particularly if it is followed by something complex, you will quickly run into performance issues.
inventory/drink/lemonade[@supplier="mother"]/price
you have to use the @ sign to indicate attribute within the predicate like so: //lemonade[@supplier="mother"]/price
, that's all.
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