Make translations a nested resource for each problem

app/controllers/translations_controller.rb

@@ -1,5 +1,6 @@
 class TranslationsController < ApplicationController
   before_action :set_translation, only: :show
+  before_action :set_problem, only: [:new, :create]
 
   # GET /translations
   # GET /translations.json
@@ -14,13 +15,13 @@ class TranslationsController < ApplicationController
 
   # GET /translations/new
   def new
-    @translation = Translation.new
+    @translation = @problem.translations.build
   end
 
   # POST /translations
   # POST /translations.json
   def create
-    @translation = Translation.new(translation_params)
+    @translation = @problem.translations.new(translation_params)
 
     respond_to do |format|
       if @translation.save
@@ -41,6 +42,10 @@ class TranslationsController < ApplicationController
 
     # Never trust parameters from the scary internet, only allow the white list through.
     def translation_params
-      params.require(:translation).permit(:title, :content, :problem_id)
+      params.require(:translation).permit(:title, :content)
+    end
+
+    def set_problem
+      @problem = Problem.find(params[:problem_id])
     end
 end

app/models/translation.rb

@@ -1,7 +1,7 @@
 class Translation < ActiveRecord::Base
   belongs_to :problem, inverse_of: :translations
 
-  validates :title, :content, :problem, presence: true
+  validates :title, :content, :problem_id, presence: true
   validates :title, uniqueness: true
 
   self.per_page = 50

app/views/translations/_form.html.erb

@@ -1,4 +1,4 @@
-<%= form_for(@translation) do |f| %>
+<%= form_for([@problem, @translation]) do |f| %>
   <% if @translation.errors.any? %>
     <div id="error_explanation">
       <h2><%= pluralize(@translation.errors.count, "error") %> prohibited this problem from being saved:</h2>

app/views/translations/index.html.erb

@@ -20,5 +20,3 @@
 </table>
 <%= render 'translation_pagination' %>
 <br>
-
-<%= link_to 'New Translation', new_translation_path, class: 'btn btn-default' %>

app/views/translations/new.html.erb

@@ -1,4 +1,4 @@
-<h1>New translation</h1>
+<h1>New translation for problem <%= @problem.id %></h1>
 
 <%= render 'form' %>
 

config/routes.rb

@@ -1,6 +1,8 @@
 Rails.application.routes.draw do
-  resources :problems, only: [:index, :show]
-  resources :translations, only: [:index, :show, :new, :create]
+  resources :problems, only: [:index, :show] do
+    resources :translations, only: [:index, :new, :create]
+  end
+  resources :translations, only: [:index, :show]
 
   # The priority is based upon order of creation: first created -> highest priority.
   # See how all your routes lay out with "rake routes".

test/controllers/translations_controller_test.rb

@@ -6,7 +6,6 @@ class TranslationsControllerTest < ActionController::TestCase
     @update = {
         title: 'New title',
         content: 'This is the new content',
-        problem_id: 1
     }
   end
 
@@ -17,13 +16,13 @@ class TranslationsControllerTest < ActionController::TestCase
   end
 
   test "should get new" do
-    get :new
+    get :new, problem_id: 1
     assert_response :success
   end
 
   test "should create translation" do
     assert_difference('Translation.count') do
-      post :create, translation: @update
+      post :create, problem_id: 1, translation: @update
     end
 
     assert_redirected_to translation_path(assigns(:translation))