Loop through a table with Simple HTML DOM - php

Question

Trying to scrape data out of a table on a website. I got the following PHP written but it isn't working.
Following error received: Notice: Trying to get property of non-object in DataScraping.php on line 27
//Sets the HTML DOM Library
require_once 'C:/xampp/php/lib/SimpleHTMLDOM/simple_html_dom.php';
$html = new simple_html_dom();
$html = file_get_html('https://www.flightradar24.com/data/flights/british-airways-ba-baw');
foreach($html->find('table[id=tbl-datatable]') as $datatable) {
foreach($datatable->find('tr') as $tr) {
foreach($tr->find('td') as $td) {
if(strpos($td->find('a', 0)->href, 'https://www.flightradar24.com/data/flights/') !== false) {
echo $td->find('a', 0)->innertext .", " .$td->find('a', 0)->href;
}
}
}
}
Also worth mentioning, this data is publically available and it is only for personal use. Please don't comment about copyright infringement - there is nothing wrong with what I want to do.
I'm simply trying to scrape the flight number only, both the inner text and the URL that sites behind it. Any help on where I'm going wrong?
Additional test provides the data I need but with the same error in between rows:
foreach($html->find('table[id=tbl-datatable]') as $datatable) {
foreach($datatable->find('tr') as $tr) {
foreach($tr->find('td') as $td) {
if (strpos($td->find('a', 0)->href, '/data/flights/') !== false) {
$test = $td->find('a', 0)->href;
$test2 = $td->find('a', 0)->innertext;
echo $test .", " .$test2;
}
}
}
}

Answer 1

You're trying to access elements of a null reference in your if statement itself, because not all of the <TD> tags have <A> tags in them. When there's no <A> tag in $td, $td->find('a', 0) is null, so
$td->find('a', 0)->href
is just what your error message said: "trying to get [a] property of [a] non-object".
You can fix this by checking the result of find() for null with an if:
$atag = $td->find('a', 0)
if ($atag) {
// ...
}
And you can fold this into your single if statement with the && operator. You've got another couple problems I found when running your code:
in the source of that site, the hrefs in the table are all relative, not absolute, so when you check for 'https://www.flightradar24.com' you find none of them
you're not adding a newline at the end of your echo
So to summarize my suggestions, something like this seems to work:
foreach($tr->find('td') as $td) {
$atag = $td->find('a', 0);
if($atag && strpos($atag->href, '/data/flights/') !== false) {
echo $atag->innertext . ", " . $atag->href . "\n";
}
}