Media Grid: on page load with `?item=` in the URL, if the model is not in the library: fetch it. Defer the triggering of `edit:attachment` until the model has been fetched.

Fixes #29052.

Built from https://develop.svn.wordpress.org/trunk@29525


git-svn-id: http://core.svn.wordpress.org/trunk@29301 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/media-grid.js

@@ -306,10 +306,20 @@
 
 		// Show the modal with a specific item
 		showItem: function( query ) {
-			var library = media.frame.state().get('library');
+			var library = media.frame.state().get('library'), item;
 
 			// Trigger the media frame to open the correct item
-			media.frame.trigger( 'edit:attachment', library.findWhere( { id: parseInt( query, 10 ) } ) );
+			item = library.findWhere( { id: parseInt( query, 10 ) } );
+			if ( item ) {
+				media.frame.trigger( 'edit:attachment', item );
+			} else {
+				item = media.attachment( query );
+				media.frame.listenTo( item, 'change', function( model ) {
+					media.frame.stopListening( item );
+					media.frame.trigger( 'edit:attachment', model );
+				} );
+				item.fetch();
+			}
 		}
 	});
 
@@ -373,9 +383,6 @@
 
 			if ( this.options.model ) {
 				this.model = this.options.model;
-			} else {
-				// this is a hack
-				this.model = this.library.at( 0 );
 			}
 
 			this.bindHandlers();