How to use post_thumbnail_url filter in WordPress

Welcome to this detailed page about the post_thumbnail_url filter in WordPress! This filter allows you to modify the post thumbnail URL dynamically. It’s like having the power to change how thumbnails appear on your site with just a few lines of code. Pretty cool, right?

post_thumbnail_url filter

Filters the post thumbnail URL.

apply_filters( 'post_thumbnail_url', string|false $thumbnail_url, int|WP_Post|null $post, string|int[] $size )

Description

This is a filter hook that filters the post thumbnail URL. It consists of three parameters: $thumbnail_url, Post ID or Post object, and $size.

It is used in get_the_post_thumbnail() which returns the post thumbnail URL.

Parameters

• $thumbnail_url: (string|false) Post thumbnail URL or false if the post does not exist.
• $post: (int|WP_Post|null) Post ID or WP_Post object. Default is global $post.
• $size: (string|int[]) Registered image size to retrieve the source for or a flat array of height and width dimensions. Default ‘post-thumbnail’.

Live Example

To run the hook, copy the example below.

apply_filters( 'post_thumbnail_url', string|false $thumbnail_url, int|WP_Post|null $post, string|int[] $size )

Example 1: Adding a Hook Callback

This example demonstrates how to add a filter callback for the post_thumbnail_url filter.

	// define the post_thumbnail_url callback 
	function weplugins_filter_post_thumbnail_url( $thumbnail_url , $post, $size) { 
	    // make filter magic happen here... 
	    return $thumbnail_url; 
	}; 
	         
	// add the filter 
	add_filter( 'post_thumbnail_url', 'weplugins_filter_post_thumbnail_url', 10, 1 ); 
	

Example 2: Modifying the Thumbnail URL

In this example, we modify the post thumbnail URL to a custom URL if certain conditions are met.

	function weplugins_custom_thumbnail_url( $thumbnail_url , $post, $size) { 
	    if ( $post->ID == 42 ) { 
	        return 'https://example.com/custom-thumbnail.jpg'; 
	    } 
	    return $thumbnail_url; 
	}; 
	         
	add_filter( 'post_thumbnail_url', 'weplugins_custom_thumbnail_url', 10, 3 ); 
	

Example 3: Removing a Hook Callback

To remove a hook callback for the post_thumbnail_url filter, use the example below.

	// remove the filter 
	remove_filter( 'post_thumbnail_url', 'weplugins_filter_post_thumbnail_url', 10, 1 ); 
	

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