Rails - Migrationcheatsheet

SHELL
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rails generate migration RemovePartNumberFromProducts part_number:string
rails generate migration remove_part_number_from_products part_number
rails generate migration AddNameToWidgets name:string
rails g migration add_name_to_widgets name:string

SHELL
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rake db:migrate

RUBY
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create_table :users do |t|
  t.string :name
  t.text   :description
  t.primary_key :id
  t.string      :title
  t.text        :description
  t.integer     :games_count
  t.float       :lol
  t.decimal     :price
  t.decimal     :price, :precision => 2, :scale => 10
  t.datetime    :expiration
  t.timestamp   :time_in
  t.time        :time_in
  t.date        :expiry
  t.binary      :image_data
  t.boolean     :is_admin
end
# Options:
  :null (boolean)
  :limit (integer)
  :default

RUBY
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add_column    :users, :first_name, :string
remove_column :users, :first_name, :string
change_column :users, :first_name, :text
change_column_default :users, :admin, nil
change_column_null    :users, :email, false # 添加不允许为空的约束
create_table
change_table
drop_table
add_column
change_column
rename_column
remove_column
add_index
remove_index

RUBY
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class AddFlagToProduct < ActiveRecord::Migration
  class Product < ActiveRecord::Base
  end
  def change
    add_column :products, :flag, :boolean
    Product.reset_column_information
    reversible do |dir|
      dir.up { Product.update_all flag: false }
    end
  end
end

RUBY
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t.references :category   # 与 t.integer :category_id 等效
  t.references :category, polymorphic: true

RUBY
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rails generate migration RemovePartNumberFromProducts part_number:string

RUBY
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add_index :suppliers, :name
add_index :accounts, [:branch_id, :party_id], :unique => true
add_index :accounts, [:branch_id, :party_id], :unique => true, :name => "by_branch_party"
add_index :accounts, :name, :name => ‘by_name’, :length => 10
add_index :accounts, [:name, :surname], :name => ‘by_name_surname’,
  :length => {
    :name => 10,
    :surname => 15
  }
add_index :accounts, [:branch_id, :party_id, :surname],
  :order =>

RUBY
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ActiveRecord::Migration.add_index :posts, :slug