Migrations

Create CRUD operations using scaffold

rails generate scaffold Article title:string description:text

Above command generates following files

Running via Spring preloader in process 6362
      invoke  active_record
      create    db/migrate/20161116062714_create_articles.rb
      create    app/models/article.rb
      invoke    test_unit
      create      test/models/article_test.rb
      create      test/fixtures/articles.yml
      invoke  resource_route
       route    resources :articles
      invoke  scaffold_controller
      create    app/controllers/articles_controller.rb
      invoke    erb
      create      app/views/articles
      create      app/views/articles/index.html.erb
      create      app/views/articles/edit.html.erb
      create      app/views/articles/show.html.erb
      create      app/views/articles/new.html.erb
      create      app/views/articles/_form.html.erb
      invoke    test_unit
      create      test/controllers/articles_controller_test.rb
      invoke    helper
      create      app/helpers/articles_helper.rb
      invoke      test_unit
      invoke    jbuilder
      create      app/views/articles/index.json.jbuilder
      create      app/views/articles/show.json.jbuilder
      create      app/views/articles/_article.json.jbuilder
      invoke  assets
      invoke    coffee
      create      app/assets/javascripts/articles.coffee
      invoke    scss
      create      app/assets/stylesheets/articles.scss
      invoke  scss
      create    app/assets/stylesheets/scaffolds.scss

rake db:migrate

delete existing scaffold

rails destroy scaffold Article

**Add foreign key when using scaffold

rails generate scaffold Comment description:text user:references

Writing migrations

rails generate migration create_articles

following migration file will be created automatically

db/migrate/20161116072421_create_articles.rb

class CreateArticles < ActiveRecord::Migration[5.0]
  def change
    create_table :articles do |t|
    end
  end
end

Add column 'title' to a Article table

class CreateArticles < ActiveRecord::Migration[5.0]
  def change
    create_table :articles do |t|
      t.string :title
    end
  end
end

run rake db:migrate

Notice changes in file db/schema.rb

ActiveRecord::Schema.define(version: 20161116072421) do

  create_table "articles", force: :cascade do |t|
    t.string "title"
  end

end

Add new column to existing table

rails generate migration add_description_to_articles

New migration file will created automatically

db/migrate/20161116074259_add_description_to_articles.rb

class AddDescriptionToArticles < ActiveRecord::Migration[5.0]
  def change
  end
end

Modify file like this

class AddDescriptionToArticles < ActiveRecord::Migration[5.0]
  def change
    add_column :articles, :description, :text
    add_column :articles, :created_at, :datetime
    add_column :articles, :updated_at, :datetime
  end
end

run rake db:migrate

Notice changes in file db/schema.rb

ActiveRecord::Schema.define(version: 20161116074259) do

  create_table "articles", force: :cascade do |t|
    t.string   "title"
    t.text     "description"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

end

rake db:rollback