Setting featured image based on related post

Question

I am using a plugin called The Events Calendar. I don't always set the featured image for each individual event. Each event has an organizer ID (tribe_get_organizer_id).

I want to add a filter that looks if an event from a custom post type (tribe_events) has a featured image attached. If not, than the filter should call up the organizer and assign the organizer's featured image as the event's featured image.

I'm not even sure with what hook to start. Something like this?

    function set_featured_event_image () {
    if ( get_post_type() == 'tribe_events') {
    if ( has_post_thumbnail() ) {
        the_post_thumbnail();
        }
        else {
GRAB THE IMAGE FROM THE RELATED ORGANIZER
        }
    }
}

    add_filter( '**WHAT HOOK?**', 'set_featured_event_image');

I might be terribly off with any of this. Any help in the right direction is appreciated.

Answer 1

I took a quick look at the Modern Tribe's source code, particularly the single-event.php view template. MT is using an internal function, tribe_event_featured_image(), which includes a filter: tribe_event_featured_image.

You could use this filter to see if MT has already found an image, and, if not, look up your own and return its value.

add_filter( 'tribe_event_featured_image', 'wpse174412', 10, 4 );
function wpse174412( $featured_image, $post_id, $size, $image_src ) {
  if ( ! $featured_image ) {
    // get image from related organizer
  }
  return $featured_image;
}

Answer 2

I found a solution, but it seems rather cumbersome. I would think a cleaner solution would be possible using WP’s native thumbnail functions, but I can’t figure it out.

When I use the “tribe_event_featured_image” function, it replaces the images well wherever that function is loaded in the templates. However, I also use for example the Genesis Framework and their Responsive Slider plugin. The solution with the tribe function didn’t populate the slider with the featured image, as that was called with the “genesis_image” function (which uses and filters WP’s thumbnail function).

That’s why I think a function that deals with the native capabilities would be better too. But here’s the code that made it possible for me to display the organizer’s featured image as the event’s featured image if no featured image was set.

    /** Define a default post thumbnail Genesis */
function default_event_image_fallback($output, $args) {
    global $post;
    if( $output || $args['size'] == 'full' && get_post_type() == 'tribe-events' )
        return $output;

    $post_id = tribe_get_organizer_id();
    $image_src = wp_get_attachment_image_src( get_post_thumbnail_id( $post_id ), $size );
    $thumbnail = $image_src[0];

    switch($args['format']) {

        case 'html' :
            return '<img src="'.$thumbnail.'" class="attachment-'. $args['size'] .'" alt="'. get_the_title($post_id) .'" />';
            break;
        case 'url' :
            return $thumbnail;
            break;
       default :
           return $output;
            break;
    }
}
add_filter('genesis_get_image', 'default_event_image_fallback', 10, 2);

/** Define a default post thumbnail Events Calendar */
function set_default_event_featured_img( $featured_image, $post_id, $size, $image_src ) {
    if ( ! $featured_image ) {
        $post_id = tribe_get_organizer_id();
        $image_src = wp_get_attachment_image_src( get_post_thumbnail_id( $post_id ), $size );
        $featured_image = '';

        //if link is not specifically excluded, then include <a>
        if ( ! empty( $image_src ) && $link ) {
            $featured_image .= '<div class="tribe-events-event-image"><a href="' . tribe_get_event_link() . '" title="' . get_the_title( $post_id ) . '"><img src="' . $image_src[0] . '" title="' . get_the_title( $post_id ) . '" /></a></div>';
        } elseif ( ! empty( $image_src ) ) {
            $featured_image .= '<div class="tribe-events-event-image"><img src="' . $image_src[0] . '" title="' . get_the_title( $post_id ) . '" /></div>';
        }

        return apply_filters( 'tribe_event_featured_image', $featured_image, $post_id, $size, $image_src );
    } 
    else {
        return $featured_image;
    }
}
add_filter( 'tribe_event_featured_image', 'set_default_event_featured_img', 10, 4 );