Get first image from last post in WordPress - php

Question

Can't get the first picture in the last post (function - get_first_post_image). Where is the mistake? Please help me. Thank you in advance for your help.
function get_first_post_image() {
global $post, $posts;
$first_img = '';
ob_start();
ob_end_clean();
if(preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches)){
$first_img = $matches [1] [0];
return $first_img;
}
else {
$first_img = "http://yyyyyy/post-default.png";
return $first_img;
}
};
function custom_function(){
$args = array(
'numberposts' => '1',
);
$recent_posts = wp_get_recent_posts( $args );
foreach( $recent_posts as $recent ):
$post_id = $recent['ID'];
$post_url = get_permalink($recent['ID']);
$post_title = $recent['post_title'];
$post_content = $recent['post_content'];
$post_thumbnail = get_the_post_thumbnail($recent['ID']);
$imglink = get_first_post_image($recent['ID']);
endforeach;
$data = '... ' . $imglink . ' ...';
....
}
Sorry for my bad English.

Answer 1

I've rewritten the function to return the default image if no first image is found. Best way of parsing HTML is DOM parsing, not regex.
function get_first_post_image(string $post_content): string
{
$defaultImage = 'http://yyyyyy/post-default.png';
libxml_use_internal_errors(true);
$doc = new DOMDocument();
$doc->loadHTML($post_content);
$img = $doc->getElementsByTagName('img');
if (!$img->length) return $defaultImage;
return $img->item(0)->getAttribute('src') ?: $defaultImage;
}
You are calling get_first_post_image() with the ID instead of the post content.
change
$imglink = get_first_post_image($recent['ID']);
to
$imglink = get_first_post_image($recent['post_content']);
I've updated the function above
Changed Signature
Removed global $post
Changed loadHtml()