Question

I have a site that needs to display the first image from any given post in a specific category. I have it working, and have added code below. My question is, is there a better way? This seems awfully kludgy.

I’m parsing the post data for whatever first appears between src=" and ". Any gotcha’s that i’m missing? Does WordPress have a better way to do this built in?

function extractStringFromString($string, $start, $end) {
//Finds the first string between $start and $end. 

    $startPos = strpos($string,$start);

    $stringEndTagPos = strpos($string,$end,$startPos);

    $stringBetween = substr($string,$startPos+strlen($start),$stringEndTagPos-$startPos-strlen($start));

    if (strlen($stringBetween) != 0 && $startPos!= '') {
        return $stringBetween;
    }
    else {
        return false;
    }



}
function getfirstimage($post){
//Returns url of first image located in post data
global $wpdb;

$sqlquery = "SELECT post_content FROM  `wp_posts` WHERE  `ID` = $post LIMIT 0 , 1";
$result = $wpdb->get_results( $sqlquery );
$result = $result[0];
$postcontent = $result->post_content;

if ($result){
    return extractStringFromString($postcontent, 'src="', '" ');
}

else return 0;

}

Answer 1

3rd Option: Use a Dom Parser

<?php
while(have_posts()) : the_post();
    $dom = new DOMDocument();
    $dom->loadHTML(get_the_content());
    $images = $dom->getElementsByTagName('img');
    $src = $images->item(0)->getAttribute('src');
    echo 'Src: '.$src.'<br/>';
    echo 'First Image: '.$images->item(0)->saveHTML();
    echo 'Image HTML: '.htmlentities($images->item(0)->saveHTML());
endwhile;
?>

This should get you started in the right direction. Regular Expressions won’t account for malformed HTML, and not all Images in your Post HTML are necessarily attachments.