Merge branch 'fix-collection_item_serializer' into 'master'

fix destroy items

See merge request !335

app/models/collection.rb

@@ -92,7 +92,7 @@ class Collection < ApplicationRecord
 
   def delete_items(items)
     items.each do |item|
-      CollectionItem.where(collection: self, collectionable: item[:type].constantize.find(item[:id])).destroy_all
+      CollectionItem.find(item[:id]).destroy
     end
   end