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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Super helpful, thanks Koren!
Happy to help! 😉
I used this today!
Awesome, Randall!
Excellent post showing the differences between the various rails generators. Clear and concise.
Thanks, happy to help!
Very Helpful! Thanks!
No problem! 😉
Very clarifying info. Didn’t know about the resource command.
Happy to help!
Very clear and to the point. Excellent explanation, love the examples of the output files. Thanks for this.
Awesome!
Very helpful, and concise! Thank you!
Happy to help!
Really 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
You’re welcome!
Thanks for this!
No prob! 😉
Thanks for such a nice explanation
i like this article because it is idiot proof
finally , 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 .
Thanks, I did not know about the resource command option, never used it till today. This help is awesome!
Cheers for clearing that one up! 😀
Wow, I just get into Rails and this is really helpful for me. Thank you so much!
I need to know the exact routes. Not the resources :… The get, post thing. Help please.
Thank You, Koren it was well worth the readand bookmarked
You’re welcome!