<Child's Parent> can't be blank while using accepts_nested_attributes_for (Rails 4)

Question

I have two models: I have a nested form that allows users to enter attributes for @contact and @goal. However, when I go to save the form input, I get the following error:

1 error prohibited this contact from being saved:
Goals contact can't be blank

Here are my goal and contact models, along with the contact controller:

class Contact < ActiveRecord::Base

  belongs_to :user
  has_many :goals
  accepts_nested_attributes_for :goals, allow_destroy: true
  validates_presence_of :user_id,:name,:title,:email
end

class Goal < ActiveRecord::Base
  belongs_to :contact
  validates_presence_of :title, :due_date, :contact_id
end

class ContactsController < ApplicationController
  before_action :set_contact, only: [:show, :edit, :update, :destroy]

  # GET /contacts
  # GET /contacts.json
  def index
    @contacts = current_user.contacts
  end

  # GET /contacts/1
  # GET /contacts/1.json
  def show
  end

  # GET /contacts/new
  def new
    @contact = Contact.new
    1.times { @contact.goals.build }
  end

  # GET /contacts/1/edit
  def edit
  end

  # POST /contacts
  # POST /contacts.json
  def create
    @contact = Contact.new(contact_params.merge(user_id: current_user.id))
    respond_to do |format|
      if @contact.save
        format.html { redirect_to @contact, notice: 'Contact was successfully created.' }
        format.json { render :show, status: :created, location: @contact }
      else
        format.html { render :new }
        format.json { render json: @contact.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /contacts/1
  # PATCH/PUT /contacts/1.json
  def update
    respond_to do |format|
      if @contact.update(contact_params)
        format.html { redirect_to @contact, notice: 'Contact was successfully updated.' }
        format.json { render :show, status: :ok, location: @contact }
      else
        format.html { render :edit }
        format.json { render json: @contact.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /contacts/1
  # DELETE /contacts/1.json
  def destroy
    @contact.destroy
    respond_to do |format|
      format.html { redirect_to contacts_url }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_contact
      @contact = Contact.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def contact_params
      params.require(:contact).permit(:name, :title, :company, :email, :notes, goals_attributes: [:title, :due_date, :notes, :contact_id])
    end
end

I made sure to add goals_attributes to the contact params (in Contacts Controller). Any thoughts on what the issue may be? Here's a link to the project: https://github.com/nowgeez/radiusapp

Thanks!

Answer 1

The clue is in the error:

Goals contact can't be blank

---

In your Goal model, you have the following validation:

validates_presence_of :title, :due_date, :contact_id

Try removing contact_id to test if it will accept or not. If it does accept, it means you're not passing the contact_id through your params to the model

We use inherited resources, which appends the parent_id automatically (if you use their belongs_to method). If you're passing the params through accepts_nested_attributes_for, I'd recommend just removing the contact_id validation, as I think it will be added as part of the process

Answer 2

I found another solution. You can use the inverse_of option within has_many and belongs_to:

class Contact < ActiveRecord::Base
  has_many :goals, inverse_of: :contact
end

class Goal < ActiveRecord::Base
  belongs_to :contact, inverse_of: :goals
  validates_presence_of :title, :due_date, :contact
end

I don't know exactly why it works, but I believe that is because it allow that contact_id is being correctly set, before Goal validation.

I found the solution reading this blog post: http://homeonrails.com/2012/10/validating-nested-associations-in-rails/