leverage the Redirection plugin database to dynamically replace links within Wordpress content with target URLs

schwifty-link-fixer-addon-for-redirection.php

<?php
//////////////////////////////////////////////////////////////////////////////////
//////////////////// 🚀 Schwifty-𝓪𝓼𝓼 Link Fixer 3000™ /////////////////////////////
//////////////////////////////////////////////////////////////////////////////////
//
// The purpose of this snippet is to leverage the Redirection plugin database to 
// dynamically replace links within Wordpress content so the site itself has as few 
// pointers to URLs that redirect as possible.
//
function schwifty_replace_old_links_in_content($content) {
    // Ensure Redirection plugin is active; if not, BAIL EARLY
    if (!is_plugin_active('redirection/redirection.php')) {
        return $content;
    }

    // Define allowed post types and specific post IDs (set to [] for all)
    $allowed_post_types = ['post']; // Modify for your use case; [] = all post types; ['post','page'] = just posts and pages etc
    $allowed_post_ids = []; // Set specific post IDs for testing or [] for all; [1,2,3] = just post ID 1, 2 and 3

    // Get the current post object
    global $post;
    if (!$post) {
        return $content;
    }

    // Check if the current post matches the post types or the allowed post ID
    if (!empty($allowed_post_types) && !in_array($post->post_type, $allowed_post_types)) {
        return $content;
    }
    if (!empty($allowed_post_ids) && !in_array($post->ID, (array) $allowed_post_ids)) {
        return $content;
    }

    // Extract all <a> tags from content
    if (preg_match_all('/<a\s[^>]*href=["\']([^"\']+)["\']/i', $content, $matches)) {
        $urls_to_check = array_unique($matches[1]); // Unique URLs only

        if (!$urls_to_check) {
            return $content; // No links to change, bail early
        }

        foreach ($urls_to_check as $old_url) {

            $redirects = Red_Item::get_for_url($old_url); // Returns an array of Red_Item objects
            if (empty($redirects) || ! is_array($redirects) || count($redirects) < 1 ) continue;

            foreach ($redirects as $redirect) {
                $action_data = $redirect->get_action_data();
                if ( $action_data === '' || $redirect->is_regex() ) continue; // @TODO needs to be fixed to handle regex matching
                $new_url = esc_url( $action_data );
                $replacements[$old_url] = $new_url;
                break; // Use the first valid redirect and move on
            }

        }

        // Only do a replacement if we found redirects
        if (!empty($replacements)) {
            foreach ($replacements as $old => $new) {
                $content = str_replace(
                    'href="' . $old . '"',
                    'href="' . $new . '" data-schwifty-oldhref="' . esc_attr($old) . '"', // keep old URL in data attribute cuz that's fun
                    $content
                );
            }
        }
    }

    return $content;
}
add_filter('the_content', 'schwifty_replace_old_links_in_content', 20);

live-replace URLs in Wordpress content using Redirection database

Requires: Redirection
This is a dirty code snippet to live-replace URLs in Wordpress content before a page is served. Please take shots at it and help this become a snippet that works for all situations. Obviously, the best thing would be to actually find/replace strings in the database, however this opens us up to corruption risk and other time-consuming cleanup if it screws up.

This lets the Redirection plugin continue handling uncaught (i.e. external) redirects while live-fixing internal links at render-time*

*this is a horrible if you’re not caching, but then again, what kind of animal are you if you’re not caching to some degree? LOL)

Known Flaws:

• Doesn’t work on regex matches yet
• Needs to work for relative URLs (this should work now but I haven’t tested it yet)
• May or may not work for links with query parameters in them. I have no idea yet.
• This is all or nothing; if you wanted to keep some links in your content pointing to URLs that redirect, this is not a solution for you.

Benefits of this add-on/snippet

1. it can be time-consuming to actually find/replace all links in your database with the new URLs
2. find/replace searches can be greedy and potentially corrupt or change unintended things ... this makes no database changes so it's safer in my opinion
3. it's usually good to have proper links on your site (i.e. without needing redirection) for SEO reasons and user experience
4. great for sites that migrated from a static site, different URL structures, etc.