Displaying every image from a WordPress post - php

Question

The goal is to have wordpress spit out or echo all of the images from a custom post format I've created. I'm new to PHP and I am not looking to use any 3rd party plugins, maybe a fix to the code provided below please.
All of the solutions I've came across from here (stackoverflow) or from google does not work or spits out ALL of the images I've ever uploaded from the media library, which I do not want. Most solutions provided are for "display the first image" which I know of and works, but I would like all of the images from a post.
Here's the closest code that sort of worked a couple of times but it deforms my layout, then goes back to displaying one image:
function displayPostImg() {
global $post, $posts;
$first_img = '';
ob_start();
ob_end_clean();
$output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);
$first_img = $matches[0][0];
return $first_img;
}
And the call I use to paste into my custom post php:
<?php echo displayPostImg(); ?>
As stated above, existing solutions do not work. Any help with a clear explination of what I am doing wrong will be a massive help.
EDIT
#corvidism Thanks for the further explanations man. I did have a look in the dev tools and the "return implode" seems to be taking it OUT of the loop, causing the layout issue. Your solution does show the post images/attachments I am after but I can't seem to fix this unfortuntaly. There seems to be this go to solution that's meant to do the same thing. This sadly echoes every image from the media library. Combining your code with this one below has gotten me close but if I come across a solution, I'll post it here for others:
$args = array(
'post_type' => 'attachment',
'posts_per_page' => -1,
'post_status' =>'any',
'post_parent' => $post->ID );
$attachments = get_posts( $args );
if ( $attachments ) {
foreach ( $attachments as $attachment ) {
echo apply_filters( 'the_title' , $attachment->post_title );
the_attachment_link( $attachment->ID , false );
}
}
EDIT #2: Solution
After messing around with various solutions, I found something that works. Try it out:
function grab_those_images( $post ) {
$content_post = $post->post_content;
$search_post = '~src="[^"]*"~';
preg_match_all( $search_post, $content_post, $imgs );
$no_of_pics = count($imgs[0]);
if ( $no_of_pics > 0 ) {
for ( $i=0; $i < $no_of_pics ; $i++ ) {
$string=$imgs[0][$i];
$string=trim( $string );
$length=strlen( $string );
$image_path=substr_replace( substr( $string, 5, $length ),"",-1 );
echo '<img src="';
echo $image_path;
echo '" />';
}
}
}

Answer 1

The function you're using contains buffer manipulation functions (ob_start() and ob_end_clean()), which and are most likely conflicting with something else in your template (probably something that's also using them, usually plugins).
Unless you're also searching for images inserted as post meta (which I assume you're not), you will find all images in a post inside the $post->post_content property. You can use preg_match_all on it to find the images.
You should pass the post content to your function as a parameter instead of accessing the global $post object. This will make things more reliable and easier to debug. (Global objects are generally frowned upon in PHP development, which is something to keep in mind if you plan to use PHP more generally than just for WordPress.)
This is how your function could look:
function getAllImagesInPost($postContent) {
preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $postContent, $matches);
// This regex function searches for <img> tags and uses a capture group
// for the image source url. It will search the whole supplied string,
// in this case post content. It returns results into the $matches variable.
$image_tags = $matches[0];
// This is an array containing all the regex matches.
$image_urls = $matches[1];
// This is an array containing all the capture group matches.
return implode('',$image_tags);
// implode() creates a string from an array of strings/numbers.
}
In your template file, the usage depends on whether or not you're in the loop. In the loop you can work with the $post object and use either $post->post_content or get_the_content() (both will get you the post content as a string):
echo getAllImagesInPost(get_the_content());
Outside of the loop you will first need to get the post (e.g. get_post($somePostID);).
Addition 1:
You must pass a variable to the function, so you can't use WordPress template functions such as the_content(). These echo directly to the page and return true or something else useless (in this case, anyway). General WP rule is that if it starts with the_ it echoes, if it starts get_the_ it returns.
Addition 2:
To display only the images from your post and no other content, you simply don't use any other content template tag in your template file. (E.g. no the_content()).
Addition 3:
I suspect your problem isn't caused by the function itself but by how/where you're calling it. But if this function does cause changes in your layout, it's 99% the regex returning broken HTML (not likely but possible, depending on your input).
The way to debug this is to inspect the page with browser dev tools and look for broken tags or other weirdness. If you see that, you need to find what exactly happens by testing the function on various input. Feed it a hard-coded string, make a test post with just text/image/anything else, until you know what's happening. If you determine that the regex is the culprit, you can try fixing it yourself or search the internet for a better one (no judgement, regex is pain).