JSON flatten to nested form fields

gistfile1.coffee

## JSON to nested form data, reset `form` before using
## Formats to `fields` requirement from `ng-file-upload`
## https://github.com/danialfarid/ng-file-upload/wiki/Rails-Example#rails-4-and-angular-file-upload-3-
form = {}

## {"test": { "sup": "bro" }} => { "test[sup]": "bro" }
json2form = (obj, root) ->
  angular.forEach obj, (v, k) ->
    key = if root then "#{root}[#{k}]" else k
    if angular.isObject(v)
      json2form(v, key)
    else
      form[key] = v

## Convert payload keys to nested form fields
json2form(payload, 'item')

console.log form