Rails converts empty arrays into nils in params of the request

Question

I have a Backbone model in my app which is not a typical flat object, it\'s a large nested object and we store the nested parts in TEXT columns in a MySQL database.

I wa

Answer 1

Here's (I believe) a reasonable solution that does not involve re-parsing the raw request body. This might not work if your client is POSTing form data but in my case I'm POSTing JSON.

in application_controller.rb:

  # replace nil child params with empty list so updates occur correctly
  def fix_empty_child_params resource, attrs
    attrs.each do |attr|
      params[resource][attr] = [] if params[resource].include? attr and params[resource][attr].nil?
    end
  end

Then in your controller....

before_action :fix_empty_child_params, only: [:update]

def fix_empty_child_params
  super :user, [:child_ids, :foobar_ids]
end

I ran into this and in my situation, if a POSTed resource contains either child_ids: [] or child_ids: nil I want that update to mean "remove all children." If the client intends not to update the child_ids list then it should not be sent in the POST body, in which case params[:resource].include? attr will be false and the request params will be unaltered.