apply_filters( 'admin_post_thumbnail_html', string $content, int $post_id, int|null $thumbnail_id )

Filters the admin post thumbnail HTML markup to return.

Parameters Parameters


(string) Admin post thumbnail HTML markup.


(int) Post ID.


(int|null) Thumbnail attachment ID, or null if there isn't one.

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Source Source

File: wp-admin/includes/post.php

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Changelog Changelog

Version Description
4.6.0 Added the $thumbnail_id parameter.
3.5.0 Added the $post_id parameter.
2.9.0 Introduced.

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User Contributed Notes User Contributed Notes

  1. Skip to note 1 content
    Contributed by Jonathan Goldford

    Below is an example of how to use this filter to provide some additional text to admins on what size image to use for their featured images. If an image is currently in place, this text will show above it. If not, the help text will show just above the “Set featured image” link.

    function filter_featured_image_admin_text( $content, $post_id, $thumbnail_id ){
        $help_text = '<p>' . __( 'Please use an image that is 1170 pixels wide x 658 pixels tall.', 'my_domain' ) . '</p>';
        return $help_text . $content;
    add_filter( 'admin_post_thumbnail_html', 'filter_featured_image_admin_text', 10, 3 );

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