⤫

Rails 4, Strong Parameters, and Nested Forms

| Tagged: rails

I recently started building a Rails 4 app and ran into some hangups when using strong parameters with nested models and forms. It seems to be lacking documentation for this specific scenario, so I wanted to share my findings.

In a scenario where you have an album that has_many songs, and you want to be able to edit both with the same form, you need to add every nested attribute that you plan to pass through to the params.permit(). This is the setup that ended up working for me:

ruby
= form_for @album do |f|
  = f.text_field :title
  = f.fields_for :songs do |s|
    = s.text_field :name
  …
ruby
class Album < ActiveRecord::Base
  has_many :songs
  accepts_nested_attributes_for :songs, allow_destroy: true
  …
end
ruby
class AlbumsController < ApplicationController
  …
  private
  def album_params
    params.require(:album).permit(:title, songs_attributes: [:id, :_destroy, :name])
  end
end
ruby
class Song < ActiveRecord::Base
  belongs_to :album
  …
end

Do you know of a better or easier way? Let me know!