Rails App From Scratch

Originally posted January 2020, but here it is now!

What they say is true - Ruby on Rails is powerful (and magical!). But to really appreciate that power and magic, you'd have to build an app from the ground up. Let's work through that initial setup of creating folders and files to get a Rails app up and running.

Let's build a coupon application, which stores coupon codes and the stores they belong to.

Create a coupon model in a folder models in a file coupon.rb:

class Coupon < ActiveRecord::Base end 

Create the table and migrate it. Go into your db folder and create a new folder, migrate, and within that folder, a new file, 001_create_coupons.rb:

class CreateCoupons < ActiveRecord::Migration def change create_table :coupons do |t| t.string :coupon_code t.string :store t.timestamps null: false end end end 

Migrate by running bin/rails db:migrate RAILS_ENV=test and look at your schema file afterwards to ensure all looks well.

Create the CouponsController located in the controllers folder:

class CouponsController < ApplicationController end 

Create the routes within the folder config and the file routes.rb:

Rails.application.routes.draw do resources :coupons, only: [:index, :show, :create, :new] end 

The resources route maps HTTP verbs to controller actions automatically - just the beginning of the magic

Start building out the CouponsController:

class CouponsController < ApplicationController def index @coupons = Coupon.all end def show @coupon = Coupon.find(params[:id]) end def new end def create @coupon = Coupon.new @coupon[:coupon_code] = params[:coupon][:coupon_code] @coupon[:store] = params[:coupon][:store] @coupon.save redirect_to coupon_path(@coupon) end end 

At any point, type rails routes in the terminal to see the created routes.

Start mapping out the views within the folder views and folder coupon and your file names will look like this:

index.html.erb new.html.erb show.html.erb 

The rest is ensuring your views display what you intend them to display, using your console for testing, and seeing what your browser displays - errors, empty content or your actual content.

Cheers to building your own Rails app from scratch, and may you enjoy the power and magic!