How to use get_canonical_url filter in WordPress

get_canonical_url filter

Filters the canonical URL for a post. To use get_canonical_url filter, first, you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin. At WePlugins, we always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_get_canonical_url_defaults which takes 2 parameters and we registered using add_filter. The first parameter get_canonical_url is the name of the hook, the second parameter modify_get_canonical_url_defaults is the name of the function which needs to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometimes, you have to remove a registered hook so you can use remove_filter to remove get_canonical_url filter.

Parameters

Below are the 2 parameters required to use this hook.

• $canonical_url : (string) The post’s canonical URL.
• $post : (WP_Post) Post object.

Example 1: Editing Canonical URLs

In this example, we modify the canonical URL based on post meta data.

    function weplugins_edit_canonical_urls( $original_url, $post ) {
        $override_url = get_post_meta( $post->ID, 'canonical_url', true );
        if ( empty( $override_url ) ) {
            return $original_url;
        }
        return $override_url;
    }
    add_filter( 'get_canonical_url', 'weplugins_edit_canonical_urls', 10, 2 );
    

Example 2: Modifying Default Canonical URL

Below is an example of how you can modify the canonical URL according to your website requirements.

    function weplugins_modify_get_canonical_url_defaults($canonical_url, $post) { 
        // Update the $canonical_url variable according to your website requirements and return this variable.
        return $canonical_url; 
    }
    // Add the filter
    add_filter( "get_canonical_url", "weplugins_modify_get_canonical_url_defaults", 10, 2 );
    

Example 3: Removing a Hook Callback

To remove a hook callback, use the example below. Make sure to provide the same callback function name, priority and number of arguments while removing the hook callback.

    remove_filter( "get_canonical_url", "weplugins_modify_get_canonical_url_defaults", 10, 2 );