How to use post_thumbnail_id filter in WordPress

post_thumbnail_id filter

Filters the post thumbnail ID.

apply_filters( 'post_thumbnail_id', int|false $thumbnail_id, int|WP_Post|null $post )

Description

This is a filter hook that filters the post thumbnail ID. It consists of two parameters: one is the thumbnail ID or false if the post does not exist, and the second is the Post ID or WP_Post object.

It is used in get_post_thumbnail_id(), which retrieves the thumbnail ID.

Parameters

• $thumbnail_id : (int|false) Post thumbnail ID or false if the post does not exist.
• $post : (int|WP_Post|null) Post ID or WP_Post object. Default is global $post.

Live Example 1: Custom Thumbnail ID

This example shows how to modify the post thumbnail ID to a custom ID if certain conditions are met.

    add_filter('weplugins_post_thumbnail_id', 'weplugins_custom_thumbnail_id', 10, 2);
    function weplugins_custom_thumbnail_id($thumbnail_id, $post) {
        if($post->post_type == 'custom_post_type') {
            return 123; // Custom thumbnail ID
        }
        return $thumbnail_id;
    }
    

Live Example 2: Default Thumbnail for Missing Posts

Use this example to set a default thumbnail ID when the post does not have one.

    add_filter('weplugins_post_thumbnail_id', 'weplugins_default_thumbnail_id', 10, 2);
    function weplugins_default_thumbnail_id($thumbnail_id, $post) {
        return $thumbnail_id ? $thumbnail_id : 456; // Default thumbnail ID
    }
    

Live Example 3: Alter Thumbnail ID Based on Post Author

In this example, we adjust the thumbnail ID based on the author’s ID.

    add_filter('weplugins_post_thumbnail_id', 'weplugins_author_based_thumbnail_id', 10, 2);
    function weplugins_author_based_thumbnail_id($thumbnail_id, $post) {
        if($post->post_author == 1) {
            return 789; // Thumbnail ID for author with ID 1
        }
        return $thumbnail_id;
    }
    

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