If you’re just learning Ruby on Rails, you may be confused as to when to generate individual models, resources or scaffolding, and what files are created by each command.
Say you want to generate a Test model with a name. You could either generate the model individually, generate resources, or generate scaffolding, as follows:
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rails g model Test name:text rails g resource Test name:text rails g scaffold Test name:text |
What’s the difference between each of the above?
Generating Individual Models
Entering rails g model Test name:text in your command line will generate the following:
(1) A model file test.rb in your models directory:
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class Test < ActiveRecord::Base end |
(2) A migration file timestamp_create_tests.rb in your db/migrate directory:
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class CreateTests < ActiveRecord::Migration def change create_table :tests do |t| t.text :name t.timestamps end end end |
Generating Resources
Entering rails g resource Test name:text in your command line will generate the following:
(1) A model file test.rb in your models directory:
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class Test < ActiveRecord::Base end |
(2) A migration file timestamp_create_tests.rb in your db/migrate directory:
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class CreateTests < ActiveRecord::Migration def change create_table :tests do |t| t.text :name t.timestamps end end end |
(3) a tests_controller.rb file in your controllers directory. This controller will be an empty shell:
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class TestsController < ApplicationController end |
(4) resources :tests routes in your routes.rb file.
Generating Scaffolding
Entering rails g scaffold Test name:text in your command line will generate the following:
(1) A model file test.rb in your models directory:
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class Test < ActiveRecord::Base end |
(2) A migration file timestamp_create_tests.rb in your db/migrate directory:
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class CreateTests < ActiveRecord::Migration def change create_table :tests do |t| t.text :name t.timestamps end end end |
(3) A tests_controller.rb file in your controllers directory. When a scaffold is generated, seven public methods and two private methods will be added to your controller:
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class TestsController < ApplicationController before_action :set_test, only: [:show, :edit, :update, :destroy] # GET /tests # GET /tests.json def index @tests = Test.all end # GET /tests/1 # GET /tests/1.json def show end # GET /tests/new def new @test = Test.new end # GET /tests/1/edit def edit end # POST /tests # POST /tests.json def create @test = Test.new(test_params) respond_to do |format| if @test.save format.html { redirect_to @test, notice: 'Test was successfully created.' } format.json { render action: 'show', status: :created, location: @test } else format.html { render action: 'new' } format.json { render json: @test.errors, status: :unprocessable_entity } end end end # PATCH/PUT /tests/1 # PATCH/PUT /tests/1.json def update respond_to do |format| if @test.update(test_params) format.html { redirect_to @test, notice: 'Test was successfully updated.' } format.json { head :no_content } else format.html { render action: 'edit' } format.json { render json: @test.errors, status: :unprocessable_entity } end end end # DELETE /tests/1 # DELETE /tests/1.json def destroy @test.destroy respond_to do |format| format.html { redirect_to tests_url } format.json { head :no_content } end end private # Use callbacks to share common setup or constraints between actions. def set_test @test = Test.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def test_params params.require(:test).permit(:name) end end |
(4) resources :tests routes in your routes.rb file.
(5) Seven corresponding view files in your views directory: (a) _form.html.erb, (b) edit.html.erb, (c) index.html.erb, (d) index.json.jbuilder, (e) new.html.erb, (f) show.html.erb and (g) show.json.jbuilder. Each view will contain html and embedded ruby.
To learn more about the routes generated by resources, please read Getting Started with Ruby on Rails.
Koren Leslie Cohen
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Brennan Zelener says
May 13, 2015 at 1:59 amSuper helpful, thanks Koren!
Koren Leslie Cohen says
May 13, 2015 at 7:41 amHappy to help! 😉
Randall says
May 17, 2015 at 9:37 amI used this today!
Koren Leslie Cohen says
May 17, 2015 at 9:55 amAwesome, Randall!
Josh Frankel says
June 5, 2015 at 11:07 amExcellent post showing the differences between the various rails generators. Clear and concise.
Koren Leslie Cohen says
June 5, 2015 at 11:08 amThanks, happy to help!
David says
July 2, 2015 at 8:02 pmVery Helpful! Thanks!
Koren Leslie Cohen says
July 2, 2015 at 8:21 pmNo problem! 😉
Francisco says
July 6, 2015 at 12:27 pmVery clarifying info. Didn’t know about the resource command.
Koren Leslie Cohen says
July 6, 2015 at 12:37 pmHappy to help!
Danny says
July 13, 2015 at 2:43 pmVery clear and to the point. Excellent explanation, love the examples of the output files. Thanks for this.
Koren Leslie Cohen says
July 13, 2015 at 2:45 pmAwesome! 🙂
Toby says
July 14, 2015 at 3:38 pmVery helpful, and concise! Thank you!
Koren Leslie Cohen says
July 14, 2015 at 3:40 pmHappy to help!
siva says
January 20, 2016 at 1:36 amReally awesome…….thank you so much………..thanks alot…i am fresher ,i started my life with ruby on rails so please suggest me and give some helpfull thing to me….my mail_id: bssp89@gmail.com
Koren Leslie Cohen says
July 23, 2016 at 3:08 amYou’re welcome!
Enrika says
February 29, 2016 at 1:38 amThanks for this!
Koren Leslie Cohen says
July 23, 2016 at 3:09 amNo prob! 😉
Raj kumar says
May 28, 2016 at 1:51 amThanks for such a nice explanation
Ben says
June 26, 2016 at 11:38 pmi like this article because it is idiot proof 🙂
motaz says
August 11, 2016 at 9:38 amfinally , someone did and told us the difference …
new to rails but i think and everyday i like it more ..
thank u very much for your kindness .
Koren Leslie Cohen says
August 16, 2016 at 7:50 pm🙂
Ad says
November 17, 2016 at 11:37 amThanks, I did not know about the resource command option, never used it till today. This help is awesome!
Jack says
December 19, 2016 at 7:03 amCheers for clearing that one up! 😀
Sang says
January 1, 2017 at 11:18 pmWow, I just get into Rails and this is really helpful for me. Thank you so much!
Angelo says
February 27, 2017 at 1:08 amI need to know the exact routes. Not the resources :… The get, post thing. Help please.
Mike says
June 13, 2017 at 3:37 amThank You, Koren it was well worth the readand bookmarked
Koren Leslie Cohen says
October 20, 2017 at 12:36 pmYou’re welcome!
Rex says
July 9, 2018 at 12:58 amthis is the best explanation I’ve seen so far, thank you so much Koren