Blog

MVC - Controller

Placeholder Avatar
Rachelle LeQuesne
February 13, 2017

Note: This post is intended as a supplement to WTF Just Happened? A Quick Tour of Your First Rails App.

MVC - Controller

As we have discussed in our article on REST and Rails, you will know that a Rails resource comes with seven standard methods for requesting data:

  • show
  • update
  • destroy
  • index
  • create
  • new
  • edit

Consequently we will need seven methods in our controllers, one for each of them. Rails knows this and provides it for you automatically. Below is the controller code that you get from running rails generate scaffold Post. You will notice that the relevant HTTP verb that we introduced in REST and Rails is included as a comment before each method.

ruby class PostsController < ApplicationController before_action :set_post, only: [:show, :edit, :update, :destroy] # GET /posts # GET /posts.json def index @posts = Post.all end # GET /posts/1 # GET /posts/1.json def show end # GET /posts/new def new @post = Post.new end # GET /posts/1/edit def edit end # POST /posts # POST /posts.json def create @post = Post.new(post_params) respond_to do |format| if @post.save format.html { redirect_to @post, notice: 'Post was successfully created.' } format.json { render :show, status: :created, location: @post } else format.html { render :new } format.json { render json: @post.errors, status: :unprocessable_entity } end end end # PATCH/PUT /posts/1 # PATCH/PUT /posts/1.json def update respond_to do |format| if @post.update(post_params) format.html { redirect_to @post, notice: 'Post was successfully updated.' } format.json { render :show, status: :ok, location: @post } else format.html { render :edit } format.json { render json: @post.errors, status: :unprocessable_entity } end end end # DELETE /posts/1 # DELETE /posts/1.json def destroy @post.destroy respond_to do |format| format.html { redirect_to posts_url, notice: 'Post was successfully destroyed.' } format.json { head :no_content } end end private # Use callbacks to share common setup or constraints between actions. def set_post @post = Post.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def post_params params.require(:post).permit(:title, :body) end end