Set Featured Image programmatically (in admin) with JavaScript?

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!

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();

        });