Query XML File using PHP for Values - php

Question

I am currently working on a project that requires me to query an XML file like php to return a value that matches the request. Take a look at the XML:
<ENVELOPE>
<MASTER>
<STKDETNAME>004-011</STKDETNAME>
<STKPNO>PTN771</STKPNO>
<STKPRICE></STKPRICE>
<STKOPBAL>500</STKOPBAL>
</MASTER>
<MASTER>
<STKDETNAME>004-012</STKDETNAME>
<STKPNO>PTN772</STKPNO>
<STKPRICE></STKPRICE>
<STKOPBAL>500</STKOPBAL>
</MASTER>
<MASTER>
<STKDETNAME>004-013</STKDETNAME>
<STKPNO>PTN773</STKPNO>
<STKPRICE></STKPRICE>
<STKOPBAL>1000</STKOPBAL>
</MASTER>
<MASTER>
<STKDETNAME>004-014</STKDETNAME>
<STKPNO>PTN774</STKPNO>
<STKPRICE></STKPRICE>
<STKOPBAL>1000</STKOPBAL>
</MASTER>
<MASTER>
<STKDETNAME>004-015</STKDETNAME>
<STKPNO>PTN775</STKPNO>
<STKPRICE>400</STKPRICE>
<STKOPBAL>1000</STKOPBAL>
</MASTER>
</ENVELOPE>
Now, I want to get the STKPRICE AND STKOPBAL for a SKTPNO= PTN773. This is what i have seen so far, but i don't know how to get the two values. I am new to XML.
$file = 'stocksum.xml';//same file as above
$xmlfile = simplexml_load_file($file);
$partno = PTN775;
$fnd = $xmlfile->xpath('/ENVELOPE/MASTER/STKPNO[.="$partno"]');

Answer 1

There are a couple of issues with the code which are just syntax problems, these are the partno needing quotes and when building the XPath expression, you use single quotes so it doesn't insert the actual part number.
BUT to get to your actual problem, if you change your XPath to the one used here, this will find the <MASTER> element whose <STKPNO> is the one your after. So then you can refer to the elements withing the <MASTER> element using standard SimpleXML object notation...
$partno = 'PTN775';
$fnd = $xmlfile->xpath('/ENVELOPE/MASTER[STKPNO="'.$partno.'"]');
echo $fnd[0]->STKPRICE.PHP_EOL;
Note that as xpath() returns a list of matches, I use $fnd[0] to get the first one.
Code which also has a check to see if the part actually exists...
$xmlfile = simplexml_load_file($file);
$partno = 'PTN7751';
$fnd = $xmlfile->xpath('/ENVELOPE/MASTER[STKPNO="'.$partno.'"]');
if ( count($fnd) == 0 ) {
echo "Not found";
}
else {
echo $fnd[0]->STKPRICE.PHP_EOL;
}