Dynamically modify Wordpress post attachment img URLs using PHP

Question

Is it possible to modify the URLs of the image attachments for the current post, so that the browser receives html with modified URLs in the img tags?

I don't want to be updating the image attachment attributes.

I'm looking for the same flexibility as exists for the post content, being that it's possible to read-in, modify then return the_content of a post.

I am aware of wp_get_attachment_image_src() and the_post_thumbnail_url() as means of fetching the attachment URL. But I can't find any means of returning a modified URL for the current post.

One possibility is to use output buffering to catch the final HTML, using ob_start() etc

But is there some more targeted method for parsing post image attachments?

MonkeySee... MonkeySee... · Accepted Answer · 2017-10-01T12:47:42

I've answered my own question using output buffering. Note I'm using a Genesis theme, so have access to additional hooks such as genesis_after_content which is after the loop and before the footer, thus the full html content is already prepared. This gives access to the featured image URLs (not possible from get_the_content) plus any/all image URLs from featured page/post widgets, etc... whatever you see in the rendered content.

<?php
//at start of php script set output buffering
ob_start();
session_start();

//script does stuff

if (isset($_SESSION['some_variable_is_set'])) {
    add_action( 'genesis_after_content', 'my_replace_image_urls');
    //used genesis_after_content hook as full html content is now prepared
}

function my_replace_image_urls() {
  $full_content = ob_get_clean();
  //modify $full_content as needed
  echo $full_content;
}

Dynamically modify Wordpress post attachment img URLs using PHP

1 Answers