Require authors to set featured image for post - php

Question

I have customised my Wordpress site design to use the featured image for posts quite excessively. This is why I need to require all post made by non-admins to require a set featured image.
How is this possible?

Answer 1

You need to hook the Publish Action in a custom PlugIn you write. Although this is to require a title, this should get you started, you just need to check if a featured image was assigned.
add_action( 'pre_post_update', 'bawdp_dont_publish' );
function bawdp_dont_publish()
{
global $post;
if ( strlen( $post->title ) < 10 ) {
wp_die( 'The title of your post have to be 10 or more !' );
}
}
Look at (has_post_thumbnail( $post->ID )) to determine if a post has a featured image.

Answer 2

Given Gary's example above, I've written the following to my functions.php file:
function featured_image_requirement() {
if(!has_post_thumbnail()) {
wp_die( 'You forgot to set the featured image. Click the back button on your browser and set it.' );
}
}
add_action( 'pre_post_update', 'featured_image_requirement' );
I'd much rather see this in a plugin as well - there's one called Mandatory Field but it doesn't work with scheduled posts. Both are not really eloquent solutions.

Answer 3

you can use a plugin
https://wordpress.org/plugins/require-featured-image/
or you can copy and paste below code in your wordpress theme functions.php file:
<?php
/**
* Require a featured image to be set before a post can be published.
*/
add_filter( 'wp_insert_post_data', function ( $data, $postarr ) {
$post_id = $postarr['ID'];
$post_status = $data['post_status'];
$original_post_status = $postarr['original_post_status'];
if ( $post_id && 'publish' === $post_status && 'publish' !== $original_post_status ) {
$post_type = get_post_type( $post_id );
if ( post_type_supports( $post_type, 'thumbnail' ) && ! has_post_thumbnail( $post_id ) ) {
$data['post_status'] = 'draft';
}
}
return $data;
}, 10, 2 );
add_action( 'admin_notices', function () {
$post = get_post();
if ( 'publish' !== get_post_status( $post->ID ) && ! has_post_thumbnail( $post->ID ) ) { ?>
<div id="message" class="error">
<p>
<strong><?php _e( 'Please set a Featured Image. This post cannot be published without one.' ); ?></strong>
</p>
</div>
<?php
}
} );