What is the error of preg_match in Xpath? Undefined offset: 1

Question

I tried to grab the id from Property ID : with the code below:

<?php
$getURL = file_get_contents('http://realestate.com.kh/residential-for-rent-in-phnom-penh-daun-penh-phsar-chas-2-beds-apartment-1001192296/');
$dom = new DOMDocument();
@$dom->loadHTML($getURL);
$xpath = new DOMXPath($dom);

/*echo $xpath->evaluate("normalize-space(substring-before(substring-after(//p[contains(text(),'Property ID:')][1], 'Property ID:'), '–'))");*/

$id = $xpath->evaluate('//div[contains(@class,"property-table")]')->item(0)->nodeValue;
preg_match("/Property ID :(.*)/", $id, $matches);

echo $matches[1];

But it doesn't work;

Notice: Undefined offset: 1 in W:\Xampp\htdocs\X\index.php on line 12

What is wrong? if I create sting like this

$id ="Property Details Property Type : Apartment Price $ 350 pm Building Size 72 Sqms Property ID : 1001192296";

And replace in my code it work. So what is the difference between data that created by myselt and grab from xpath? Thank in advance for help me.

Answer 1

Your preg_match() does not work because the nodeValue from the xpath you are getting is exactly this:

Property Details

                            Property Type : 
                         Apartment 


                    Price
                    $ 350 pm


                Building Size
                72 Sqms


                Property ID 
                 : 
                1001192296

So you have to try it like this:

$getURL = file_get_contents('http://realestate.com.kh/residential-for-rent-in-phnom-penh-daun-penh-phsar-chas-2-beds-apartment-1001192296/');
$dom = new DOMDocument();
@$dom->loadHTML($getURL);
$xpath = new DOMXPath($dom);

/*echo $xpath->evaluate("normalize-space(substring-before(substring-after(//p[contains(text(),'Property ID:')][1], 'Property ID:'), '–'))");*/

$id = $xpath->evaluate('//div[contains(@class,"property-table")]')->item(0)->nodeValue;

$id = preg_replace('!\s+!', ' ', $id);

preg_match("/Property ID :(.*)/", $id, $matches);

echo $matches[1];

This ( $id = preg_replace('!\s+!', ' ', $id); ) will combine all tabs, whitespaces between the words to one whitespace.

Update: Due to the comment below, I now get the full text of the HTML with $xpath->evaluate() and try to match all property ids ( like only digit and P-digits ).

$getURL = file_get_contents('http://realestate.com.kh/residential-for-rent-in-phnom-penh-daun-penh-phsar-chas-2-beds-apartment-1001192296/');

$dom = new DOMDocument();
@$dom->loadHTML($getURL);

$xpath = new DOMXPath($dom);

// this only returns the text of the whole page without html tags
$id = $xpath->evaluate( "//html" )->item(0)->nodeValue;
$id = preg_replace('!\s+!', ' ', $id);

// not a good regex, but matches the property IDs
preg_match_all("/Property ID( |):[ |]((\w{0,1}[-]|)\d*)/", $id, $matches);

// after the changes you have to go for the matches is $matches[2]
foreach( $matches[2] as $property_id ) {
    echo $property_id."<br>";
}