intridea/grape — pull request #812 by faucct (2014-11-13 08:35:47+00:00)
Title: try to convert string parameter to an array or hash if they are expected

The multipart post requests from Angular.JS send the arrays in the json format (like tag_ids=[1,2], not tag_ids[]=1&tag_ids[]=2) which is not getting recognized. If an array or hash is expected while the string is provided, I try to convert it from the JSON.
Found this one using the angular-file-upload gem (https://github.com/danialfarid/angular-file-upload).