#1 #2 #4 バックエンド資産作成

backend/app/controllers/application_controller.rb

@@ -0,0 +1,2 @@
+class ApplicationController < ActionController::API
+end

backend/app/controllers/posts_controller.rb

@@ -0,0 +1,27 @@
+class PostsController < ApplicationController
+  before_action :set_post, only: [:good, :bad, :destroy]
+
+  # POST /posts/:id/good
+  def good
+    @post.increment!(:good)
+    head :no_content
+  end
+
+  # POST /posts/:id/bad
+  def bad
+    @post.increment!(:bad)
+    head :no_content
+  end
+
+  # DELETE /posts/:id
+  def destroy
+    @post.update!(deleted_at: Time.current)
+    head :no_content
+  end
+
+  private
+
+  def set_post
+    @post = Post.active.find(params[:id])
+  end
+end

backend/app/controllers/thread_posts_controller.rb

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+class ThreadPostsController < ApplicationController
+  before_action :set_thread
+
+  # GET /api/threads/:thread_id/posts
+  def index
+    sort = params[:sort].presence_in(['created_at', 'score']) || 'created_at'
+    order = params[:order].presence_in(['asc', 'desc']) || 'desc'
+
+    posts = @thread.posts
+            .select('posts.*, (good - bad) AS score')
+            .order("#{ sort } #{ order }")
+
+    render json: posts
+  end
+
+  # POST /api/threads/:thread_id/posts
+  def create
+    post = @thread.posts.new(post_params)
+    if post.save
+      render json: post, status: :created
+    else
+      render json: { errors: post.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+  def set_thread
+    @thread = Topic.find(params[:thread_id])
+  end
+
+  def post_params
+    params.require(:post).permit(:name, :body, :password)
+  end
+end

backend/app/controllers/threads_controller.rb

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+class ThreadsController < ApplicationController
+  # GET /api/threads
+  def index
+    threads = Topic.order(updated_at: :desc)
+    render json: threads
+  end
+
+  # GET /api/threads/:id
+  def show
+    thread = Topic.find(params[:id])
+    render json: thread
+  end
+
+  # POST /api/threads
+  def create
+    thread = Topic.new(thread_params)
+    if thread.save
+      render json: thread, status: :created
+    else
+      render json: { errors: thread.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+  def thread_params
+    params.require(:thread).permit(:title, :description)
+  end
+end