megabrutal

Meanwhile, I figured it out myself.

I wrote a small plugin that does the work:

<?php
/*
Plugin Name: Replace Custom Field By Database Entry
Version: 0.1
Author: MegaBrutal
*/

function rcfbde_install () {
	global $wpdb;

	$table_name = $wpdb->prefix . "cftolink";
	$sql = "CREATE TABLE IF NOT EXISTS '" . $table_name . "' (
			'id' mediumint unsigned NOT NULL AUTO_INCREMENT,
			'title' text NOT NULL,
			'url' text DEFAULT NULL,
			PRIMARY KEY ('id')
		);";

	$sql = $wpdb->prepare($sql);
	$wpdb->query($sql);
}

function filter_rcfbde ($line, $key, $value) {
	global $wpdb;

	$table_name = $wpdb->prefix . "cftolink";

	$valuet = trim($value);
	if ('_' == $valuet[0]) {
		$valuen = substr($valuet, 1);
		$row = wp_cache_get($valuen, "cftolink");
		if (false == $row) {
			$sql = $wpdb->prepare("SELECT * FROM '" . $table_name . "' WHERE 'id'=" . $valuen . ";");
			$row = $wpdb->get_row($sql);
			wp_cache_set($valuen, $row, "cftolink");
		}

		if (is_null($row->url)) {
			$line = str_replace($value, $row->title, $line);
		} else {
			$ahref = "<a href=\"" . $row->url . "\">" . $row->title . "</a>";
			$line = str_replace($value, $ahref, $line);
		}
	}
	return $line;
}

register_activation_hook(__FILE__, 'rcfbde_install');
add_filter('the_meta_key', 'filter_rcfbde', 1, 3);
?>

I hope I chose the most efficient solution.

I don’t really get it… I’ve added a the_meta() call in my templates so my metadatas are shown well. My problem is that I wouldn’t like to add the exact same and long metadata values to a bunch of posts. It’s inconvenient, redundant, and it would be a problem if I’d need to change these metas for all posts for some reason.

You have several options:
1. Login to phpMyAdmin, and manually change the “siteurl” and “home” records in the wp_options table.
2. Open up wp-config.php, and add these lines:

define('WP_HOME','https://your.correct.url.com/path/to/wordpress');
define('WP_SITEURL','https://your.correct.url.com/path/to/wordpress');

Then you may access your site. Go to admin, change back the site url on the admin page as well, then remove the above lines from your wp-config.php.

For more options, see: https://codex.www.ads-software.com/Changing_The_Site_URL

Thanks, it helped! ??