Replace : if (!is_object($post)) return $settings;

By: if ( isset( get_current_screen()->post_type ) && (get_current_screen()->post_type == ‘YOUR POST TYPE’ ) ) {
$post = get_post( $_GET[‘post’] );
}

Explanation: If you use a custom post type like i was ‘$post’ will always be a non-object and you’re not gonna be able to pass the if.

—
For those who don’t get how to have a shortcode string, that’s simple. Juste use a basic shortcode like : [gallery ids="729,732,731,720"]. The numbers are ids of attachments you want to show.

Here is my personal code. It’s not gonna resolve all issues but it’s easily adaptable:

$imageIdsArray = json_decode(get_post_meta($post->ID, “_gallery_medias_ids”, true));

// i previously saved my images using json_encode (to transform my array of // ids into a string like ‘[729,732]’ in database

if( !empty( $imageIdsArray ) ) {
$imageIds = implode($imageIdsArray, ‘ , ‘);
$shortcode = ‘[gallery ids="'. $imageIds .'"]‘;
$settings[‘myGallery’] = array(‘shortcode’ => $shortcode);
}
return $settings;

—
Finally in your .js file put:
var shortcode = wp.shortcode.next( ‘gallery’, wp.media.view.settings.myGallery.shortcode )

And you’ll be fine 🙂

—
Thanks to the author ! You made the most comprehensible documentation about wp.media manipulation and i’m writing this comment in 2016 (!!)

thanks you.

// Create our own shortcode string here
$shortcode = ...

How do I generate the shortcode?

I’m stuck with this:
wp.media.post( ‘shiba-mlib-gallery-update’, {
nonce: wp.media.view.settings.post.nonce,
html: wp.media.shibaMlibEditGallery.link,
post_id: wp.media.view.settings.post.id,
ids: ids
}).done( function() {
window.location = wp.media.shibaMlibEditGallery.link;
});

and this:
add_action( ‘wp_ajax_shiba-mlib-gallery-update’,
array($this,’wp_ajax_shiba_mlib_gallery_update’));

wp.media.shibaMlibEditGallery.link returns undefined.

Do you mind giving an example setting of wp.media.shibaMlibEditGallery.link and implementation of wp_ajax_shiba_mlib_gallery_update.

I really appreciate it so much. Thanks again 🙂

I do not properly understand the 2nd part (2. Get Initial Gallery Images) at all. I am not using your plugin/theme, but want to use the code on the front end. I mastered step 1 ok – so I get the media modal, but there are no proper explanations for step 2. I would like to only show the uploaded images to the post that is just being viewed. Is there a good way to do this? Apart from that the explanations are very detailed and very helpful!
Thanks,
Sascha