How to perform XPath on individual elements in PHP using SimpleXML? - php

Question

I have the following example XML document:
<?xml version="1.0" encoding="UTF-8" ?>
<database>
<record>
<id>1</id>
<a>5</a>
</record>
<record>
<id>5</id>
<a>8</a>
</record>
<record>
<id>7</id>
<!--No a record!-->
</record>
<record>
<id>6</id>
<a>10</a>
</record>
</database>
I want to iterate through each "record" element and fetch it's corresponding "a" element if it exists.
I attempted this using the following code:
$xml = new SimpleXMLElement($xmlStringDataFromFile);
foreach ($xml->record as $record) {
$id = $record->xpath("//id")[0];
$a = $record->xpath("//a")[0];
echo "{$id}: {$a}\n";
}
However the xpath performed is on the entire document. not on the individual "record" element. Thus I got the following output:
1: 5
1: 5
1: 5
1: 5
I want the following output:
1: 5
5: 8
7:
6: 10
How do I do this?

Answer 1

When you use // at the beginning of the XPath expression it will search from the document root and you always end up with the same result. Since the id and a elements are directly under record simply use
$id = $record->xpath("id")[0];
$a = $record->xpath("a")[0];
If they would be at same level below record start the XPath expression with a . to search relative to the context node:
$id = $record->xpath(".//id")[0];
$a = $record->xpath(".//a")[0];