Set Featured Image programmatically (in admin) with JavaScript?

Question

I'm trying to set the post thumbnail (featured image) with javascript from an existing image in the media gallery. I would consider a php-based option too I suppose (one that would require clicking update before the images show up).

Some Background

I'm building a site for a music venue with a custom "event" post-type. Most of the time these events are unique, but there are some recurring ideas (for example, open mic night most tuesdays).

I was thinking I'd like to put in a dropdown with some "presets" to populate the add new event form fields in the backend. It's a cinch (I think) to do this with the the tinymce, and my custom meta fields. The tough part is how to to put an (already uploaded to media library) image into the featured image box programmaticly.

I know I can do make something work on the template end of things, but it would be nice to see that thumbnail pop up in the add new/edit view.

Thanks!

Answer 1

You need to do an ajax call with action: 'set-post-thumbnail'

Check in admin-ajax.php (line 1477 in 3.3.2) for the expected values and nonce, but in general you need to send post_id, attachment_id and nonce.

The nonce should come from: wp_create_nonce( "set_post_thumbnail-$post_id" );

The admin does something like:

 uploader.bind('FileUploaded', function(up, file, response) {
            jQuery.post(ajaxurl, {
                    action:"set-post-thumbnail", post_id: post_id, thumbnail_id: response.response, _ajax_nonce: '<?php echo $ajax_nonce;?>' , cookie: encodeURIComponent(document.cookie)
                }, function(str){
                    var win = window.dialogArguments || opener || parent || top;
                    if ( str == '0' ) {
                        alert( setPostThumbnailL10n.error );
                    } else {
                         jQuery('#postimagediv .inside').html(str);
                         jQuery('#postimagediv .inside #plupload-upload-ui').hide();

                    }
                }
                );
                jQuery("#postimagediv .inside h2.uploading_message").remove();

        });

Answer 2

I think update_post_meta function will make the attachment featured.

update_post_meta($post_id, '_thumbnail_id', $attachment_id);

Answer 3

You could display the images in a jquery image combobox, have the user click 'update,' and then use set_post_meta or update_post_meta to put the image in the post.

If you don't want to add an extra button you could use the solution to this question to save the meta data for your custom post type.

Answer 4

This solution didn't exist at the time this question was asked, but since I was led here in my quest to find an answer, I figure it might help someone else.

I'm not sure how to capture the upload event as I'm using CMB2's event cmb_media_modal_select, but setting the featured image is as simple as:

wp.media.featuredImage.set(id)

More on this portion of the JS API here.

For me, with CMB2, I am using the following:

$( document ).on( 'cmb_media_modal_select', function ( e, selection, media ) {
    let currentMediaId = wp.media.featuredImage.get();

    if( currentMediaId === -1 ) {
        let newMediaId = selection.models[ 0 ].id;
        console.log( newMediaId );
        wp.media.featuredImage.set( newMediaId );
    }
} );

Hope this helps someone!