Rails Generators

The rails generate command, or rails g saves you alot of time writing the same thing every time you create a new app. It literally gives you power…to create amazing apps with less physical effort.

Model

Let’s say we’re setting up our app’s backend and we want to generate a Post model. Running rails generate model Post title body will show the following in your terminal:

 invoke active_record
 create db/migrate/20220808114022_create_posts.rb
 create app/models/post.rb
 invoke test_unit
 create test/models/post_test.rb
 create test/fixtures/posts.yml

And create these files:

********* db/migrate/20220808114022_create_posts.rb
class CreatePosts < ActiveRecord::Migration[7.0]
def change
create_table :posts do |t|
t.string :title
t.string :body
t.timestamps
end
end
end
*************app/models/post.rb
class Post < ApplicationRecord
end

Resource

Say you ran

rails g resource User username password_digest

This is what would show in the terminal:

invoke active_record
 create db/migrate/20220808114816_create_users.rb
 create app/models/user.rb
 invoke test_unit
 create test/models/user_test.rb
 create test/fixtures/users.yml
 invoke controller
 create app/controllers/users_controller.rb
 invoke erb
 create app/views/users
 invoke test_unit
 create test/controllers/users_controller_test.rb
 invoke helper
 create app/helpers/users_helper.rb
 invoke test_unit
 invoke resource_route
 route resources :users

And all these files ready for you in your editor:

**********db/migrate/20220808114816_create_users.rb
class CreateUsers < ActiveRecord::Migration[5.2]
  def change
    create_table :users do |t|
      t.string :name
      t.string :username
      t.string :password_digest
  t.timestamps
    end
  end
************* app/models/user.rb
class User < ApplicationRecord
end
**************app/controllers/users_controller.rb
class UsersController < ApplicationController
end
***************routes in config/routes.rb
Rails.application.routes.draw do
  resources :users
end

Scaffold

Now this is where things get interesting or wild depending on what programming framework you were using before.

Scaffold generates everything resource generates plus a controller with public methods for basic CRUD operations as well as a few private methods.

Running

rails g scaffold User username password_digest 

brings forth this in the controllers folder:

class UsersController < ApplicationController
  before_action :set_user, only: [:show, :update, :destroy]
# GET /users
  def index
    @users = User.allrender json: @users
  end
# GET /users/1
  def show
    render json: @user
  end
# POST /users
  def create
    @user = User.new(user_params)if @user.save
      render json: @user, status: :created, location: @user
    else
      render json: @user.errors, status: :unprocessable_entity
    end
  end
# PATCH/PUT /users/1
  def update
    if @user.update(user_params)
      render json: @user
    else
      render json: @user.errors, status: :unprocessable_entity
    end
  end
# DELETE /users/1
  def destroy
    @user.destroy
  end
private
    # Use callbacks to share common setup or constraints between actions.
    def set_user
      @user = User.find(params[:id])
    end# Only allow a trusted parameter "white list" through.
    def user_params
      params.require(:user).permit(:name, :username, :email)
    end
end