RoR4: NoMethodError in nested resources' view

Question

I have a parent/children relationship model with nested resources setup in order to create child data under a certain parent from it's show page. However, when I click on the child's new page link from the parent page ("http://localhost:3000/brands/1/restaurants/new"), I get an error saying that "NoMethodError in...". Please help.

config/routes.rb

Rails.application.routes.draw do
  resources :brands, shallow: true do
        resources :restaurants
  end
  resources :managers 

#               Prefix Verb   URI Pattern                                 Controller#Action
#    brand_restaurants GET    /brands/:brand_id/restaurants(.:format)     restaurants#index
#                      POST   /brands/:brand_id/restaurants(.:format)     restaurants#create
# new_brand_restaurant GET    /brands/:brand_id/restaurants/new(.:format) restaurants#new
#      edit_restaurant GET    /restaurants/:id/edit(.:format)             restaurants#edit
#           restaurant GET    /restaurants/:id(.:format)                  restaurants#show
#                      PATCH  /restaurants/:id(.:format)                  restaurants#update
#                      PUT    /restaurants/:id(.:format)                  restaurants#update
#                      DELETE /restaurants/:id(.:format)                  restaurants#destroy
#               brands GET    /brands(.:format)                           brands#index
#                      POST   /brands(.:format)                           brands#create
#            new_brand GET    /brands/new(.:format)                       brands#new
#           edit_brand GET    /brands/:id/edit(.:format)                  brands#edit
#                brand GET    /brands/:id(.:format)                       brands#show
#                      PATCH  /brands/:id(.:format)                       brands#update
#                      PUT    /brands/:id(.:format)                       brands#update
#                      DELETE /brands/:id(.:format)                       brands#destroy
#             managers GET    /managers(.:format)                         managers#index
#                      POST   /managers(.:format)                         managers#create
#          new_manager GET    /managers/new(.:format)                     managers#new
#         edit_manager GET    /managers/:id/edit(.:format)                managers#edit
#              manager GET    /managers/:id(.:format)                     managers#show
#                      PATCH  /managers/:id(.:format)                     managers#update
#                      PUT    /managers/:id(.:format)                     managers#update
#                      DELETE /managers/:id(.:format)                     managers#destroy                     managers#destroy
end

models/brand.rb

class Brand < ActiveRecord::Base
    has_many :restaurants
end

models/restaurants.rb

class Restaurant < ActiveRecord::Base
    belongs_to :brand
end

controllers/restaurants_controller.rb

class RestaurantsController < ApplicationController
  before_action :set_restaurant, only: [:new, :create, :show, :edit, :update, :destroy]

  # GET /restaurants
  # GET /restaurants.json
  def index
    @restaurants = Restaurant.all
  end

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

  # GET /restaurants/new
  def new
    # @restaurant = Restaurant.new
    @restaurant = Restaurant.new
  end

  # GET /restaurants/1/edit
  def edit
  end

  # POST /restaurants
  # POST /restaurants.json
  def create
    @restaurant = Restaurant.new(restaurant_params)

    respond_to do |format|
      if @restaurant.save
        format.html { redirect_to brands_path, notice: 'Restaurant was successfully created.' }
        format.json { render :show, status: :created, location: @restaurant }
      else
        format.html { render :new }
        format.json { render json: @restaurant.errors, status: :unprocessable_entity }
      end
    end
  end

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

  # DELETE /restaurants/1
  # DELETE /restaurants/1.json
  def destroy
    @restaurant.destroy
    respond_to do |format|
      format.html { redirect_to restaurants_url, notice: 'Restaurant was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_restaurant
      @restaurant = Restaurant.find_by(params[:brand_id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def restaurant_params
      params.require(:restaurant).permit(:name, :brand_id) if params[:restaurant]
    end
end

views/brands/show.html

<p id="notice"><%= notice %></p>

<p>
  <strong>Name:</strong>
  <%= @brand.name %>
</p>

<p>
  <strong>Manager:</strong>
  <%= @brand.manager_id %>
</p>

  <table>
    <% @brand.restaurants.each do |restaurant| %>
      <tr>
        <td><%= restaurant.name %></td>
        <td><%= restaurant.brand_id %></td>
        <td><%= link_to 'Show', restaurant %></td>
        <td><%= link_to 'Edit', edit_restaurant_path(restaurant) %></td>
        <td><%= link_to 'Destroy', restaurant, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </table>
 <br>
**<%= link_to 'Add New Restaurant', new_brand_restaurant_path(@brand) %>**
<%= link_to 'Edit', edit_brand_path(@brand) %> |
<%= link_to 'Back', brands_path %>

What did I do wrong? Appreciate your help.

Addin Full Error Message:

NoMethodError in Restaurants#new Showing /Users/kaku/sample/relation/app/views/restaurants/_form.html.erb where line #1 raised:

undefined method `restaurants_path' for

<#:0x007fd4ec2e46e0> Extracted source (around line #1): 1 2 3 4 5 6

           <%= form_for(@restaurant) do |f| %>

<% if @restaurant.errors.any? %>

<%= pluralize(@restaurant.errors.count, "error") %> prohibited this restaurant from being saved:

Trace of template inclusion: app/views/restaurants/new.html.erb

Rails.root: /Users/kaku/sample/relation

Application Trace | Framework Trace | Full Trace app/views/restaurants/_form.html.erb:1:in _app_views_restaurants__form_html_erb__1732550980462972679_70276222510780' app/views/restaurants/new.html.erb:3:in _app_views_restaurants_new_html_erb___209183791776779444_70276222559000' Request

Parameters:

{"brand_id"=>"2"} Toggle session dump _csrf_token: "MG3xNH+mscxxPiQqLVkF011BDb5RGlWJPuTN3GiEcGo=" session_id: "e1f92f37d231a058162af62bae976ff5" Toggle env dump GATEWAY_INTERFACE: "CGI/1.1" HTTP_ACCEPT: "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8" HTTP_ACCEPT_ENCODING: "gzip, deflate, sdch" HTTP_ACCEPT_LANGUAGE: "ja,en-US;q=0.8,en;q=0.6" REMOTE_ADDR: "::1" REMOTE_HOST: "::1" SERVER_NAME: "localhost" SERVER_PROTOCOL: "HTTP/1.1" Response

Headers:

None

Answer 1

As you pointed in the code, I believe the error is in this line

<%= link_to 'Add New Restaurant', new_brand_restaurant_path(@brand) %>

You should have @brand in the new method of restaurants_controller

def new
  @brand = Brand.find(params[:brand_id]) 
  @restaurant = Restaurant.new
end

And also I noticed that you have defined set_restaurant wrongly. It should be

def set_restaurant
  @restaurant = Restaurant.find(params[:id])
end

Update:

undefined method `restaurants_path'

You have nested resources, so this line

<%= form_for(@restaurant) do |f| %>

should be

<%= form_for [@brand, @restaurant] do |f| %>