[Rails] Migration command summary

Development environment

・ Ruby: 2.5.7 Rails: 5.2.4 ・ Vagrant: 2.2.7 -VirtualBox: 6.1 ・ OS: macOS Catalina

How to write a migration command

$ rails g migration ChangeColumnToBooks is Same as writing $ rails generation migration change_column_to_books.

In other words, generation can be abbreviated as g, Like ʻAddBodyToBooks`, you can save the trouble of writing" _ "by capitalizing the beginning of a word.

Basic commands

1. Create model and table

$ rails g model model name column name: type name

Terminal

$ rails g model Book title:string

migrate/~_create_books.rb

class CreateBooks < ActiveRecord::Migration[5.2]
  def change
    create_table :books do |t|
      t.string :title

      t.timestamps
    end
  end
end

2. Delete model and table

rails d model model name

Terminal

$ rails d model Book

3. Execute migration

Terminal

$ rails db:migrate

4. Return the contents of the migration

** ① When going back one step **

Terminal

$ rails db:rollback

** ① When returning to multiple steps **

Terminal

$ rails db:rollback STEP=5 #Numbers can be changed freely

4. Check migration status

Terminal

rails db:migrate:status

Table relation

1. Delete only the table

$ rails g migration Drop table name

Terminal

$ rails g migration DropBooks

migrate/~_drop_books.rb

class DropBooks < ActiveRecord::Migration[5.2]
  def change
    drop_table :books #Postscript
  end
end

2. Change the table name

$ rails g migration Rename Table name before change To Table name after change

Terminal

$ rails g migration RenameBooksToArticles

migrate/~_rename_books_to_articles.rb

class RenameBooksToArticles < ActiveRecord::Migration[5.2]
  def change
    rename_table :books, :articles #Postscript
  end
end

Column relation

1. Add column

** ① Single **

$ rails g migration Add Column name To Table name Column name: Type name

Terminal

$ rails g migration AddBodyToBooks body:text

migrate/~_add_body_to_books.rb

class AddBodyToBooks < ActiveRecord::Migration[5.2]
  def change
    add_column :books, :body, :text
  end
end

** ② Multiple **

$ rails g migration AddColumnsTo Table name Column name: Type name Column name: Type name Column name: Type name

Terminal

$ rails g migration AddColumnsToBooks body:text introduction:text price:integer

migrate/~_add_columns_to_books.rb

class AddColumnsToBooks < ActiveRecord::Migration[5.2]
  def change
    add_column :books, :body, :text
    add_column :books, :introduction, :text
    add_column :books, :price, :integer
  end
end

2. Delete column

** ① Single **

$ rails g migration Remove Column name From table name Column name: Type name

Terminal

$ rails g migration RemoveTitleFromBooks title:string

migrate/~_remove_title_from_books.rb

class RemoveTitleFromBooks < ActiveRecord::Migration[5.2]
  def change
    remove_column :books, :title, :string
  end
end

** ② Multiple **

$ rails g migration RemoveColumnsFrom table name column name: type name column name: type name column name: type name

Terminal

$ rails g migration RemoveColumnsFromBooks body:text introduction:text price:integer

migrate/~_remove_columns_from_books.rb

class RemoveColumnsFromBooks < ActiveRecord::Migration[5.2]
  def change
    remove_column :books, :body, :text
    remove_column :books, :introduction, :text
    remove_column :books, :price, :integer
  end
end

3. Change column data type

$ rails g migration ChangeData Column name To Table name Column name: Type name

Terminal

$ rails g migration ChangeDataTitleToBooks

migrate/~_change_data_title_to_books.rb

class ChangeDataTitleToBooks < ActiveRecord::Migration[5.2]
  def change
    change_column :books, :title, :text #Postscript
  end
end

4. Added column options

$ rails g migration ChangeOption Column name To Table name Column name: Type name

Terminal

$ rails g migration ChangeOptionTitleToBooks

migrate/~_change_option_title_to_books.rb

class ChangeOptionTitleToBook < ActiveRecord::Migration[5.2]
  def change
    change_column :books, :title, :string, null: false #Postscript
  end
end

5. Data type list

6. Frequently used options