Backbone and Rails associations: Avoiding JSON HashWithIndifferentAccess errors

Question

I\'m trying to get my backbone associations working inside a rails app , and I\'m having difficulty when trying to update existing models. Specifically, Rails throws the followi

Answer 1

I dealt with the same issue recently. It's actually not a HashWithIndifferentAccess error: it has to do with how accepts_nested_attributes_for expects params.

When you declare accepts_nested_attributes_for :comments, Rails looks for a parameter call comments_attributes on the incoming params.

The problem is that your JSON representation coming from Backbone has a "comments" property instead of a "comments_attributes" property.

You could fix it on the Backbone side by adding a toJSON function to your Post model:

# in your Post model
toJSON: ->
  attrs = _.clone(@attributes)
  attrs.comments_attributes = _.clone(@attributes.comments)
  delete attrs.comments
  attrs

Or you could handle it in your Rails controller:

# in your Posts controller
def update
  params[:comments_attributes] = params.delete(:comments) if params.has_key? :comments
  # call to update_attributes and whatever else you need to do
 end

Hopefully this helps.