Rails：嵌套模型表单未创建记录

Question

I'm trying to create a form that can both update an 'Invite' and add a new 'Guest' (a nested form). An 'Invite' has_many 'Guests' and 'Guests' belong_to 'Invites'. I've gone through setting up accepts_nested_attributes_for but I cannot get the form to add a new 'Guest'.

At the moment the from can update the Invite but just directs to the 'show' view, but does not add a new Guest record. and I'm not sure why. I have a feeling it has something to do with the Invite 'update' method...

Here's some code:

Invite model:

class Invite < ActiveRecord::Base
  has_many :guests
  def invite_params

  def invite_params
    params.require(:invite).permit(:invite_code, :name)
  end

  accepts_nested_attributes_for :guests

  validates :invite_code, presence: true, numericality: true, length: { is: 4 }
  validates :name, presence: true, length: { minimum: 5 }
 end

Guest model:

class Guest < ActiveRecord::Base
  belongs_to :invite

  def guest_params
    params.require(:guest).permit(:name, :attendance_status, :starter, :main, :desert, :dietary_requirements)
  end

  validates :name, presence: true, length: { minimum: 5 }
  validates :attendance_status, presence: true
end

Form:

<%= form_for @invite, url: invite_path(@invite), method: :patch do |invite_form| %>
  <p>
    <%= invite_form.label :name %><br>
    <%= invite_form.text_field :name %>
  </p>

  etc...

  <%= invite_form.fields_for :guest do |guest_form| %>
    <h3>Add a Guest</h3>
    <p>
      <%= guest_form.label :name %><br>
      <%= guest_form.text_field :name %>
    </p>

    etc...
  <% end %>

  <%= invite_form.submit 'Update' %>

<% end %>

Guest controller:

class GuestsController < ApplicationController
 def new
   @invite = Invite.find(params[:invite_id])
   @guest = @invite.guests.build
 end

 def create
   @invite = Invite.find(params[:invite_id])
   @guest = @invite.guests.create(guest_params)
   redirect_to edit_invite_path(@invite)
 end

 etc...

Invite controller:

def update
 @invite = Invite.find(params[:id])

 if @invite.update(invite_params)
   redirect_to @invite
 else
   render 'edit'
 end
end

I'm guessing this is something to do with the controller method but I can't figure out what?

Any help appreciated...

Answer 1

Firstly, you need to move your params declarations to your invite controller, where Rails 4 intends them to be.

Your params will need to take the nested attributes in a single params call. If that's confusing, check out this SO question and see in the answers how to nest those attributes.

Make sure your form has ...fields_for :guests , too, as your Invite class has_many :guests

So, your invite_params implementation might end up looking something like this:

def invite_params
  params.require(:invite).permit(:invite_code, :name, guests_attributes:[:name, :attendance_status, :starter, :main, :desert, :dietary_requirements])
end

Answer 2

Are you using Rails 4? If so read up on strong parameters. Should look something like this in your invite controller.

private

  def invite_params
    params.require(:invite).permit(:invite_code, :name, guests_attributes:[:name, :attendance_status, :starter, :main, :desert, :dietary_requirements])
  end