Automatically make migrations
$ rails generate migration RemovePartNumberFromProducts part_number:string
$ rails generate migration remove_part_number_from_products part_number # rails assumes string if not type given - and you can use snake_case
$ rails generate migration AddNameToWidgets name:string
$ rails g migration add_name_to_widgets name:string # you can use the short cut 'g' instead of generate - they both do the same thing
Run migrations
$ rake db:migrate
Creating tables
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
Operations
add_column :users, :first_name, :string
remove_column :users, :first_name, :string
change_column :users, :first_name, :text
change_column :users, :first_name, :text
change_column_default :users, :admin, nil
change_column_null :users, :email, false # adds NOT NULL constraint
create_table
change_table
drop_table
add_column
change_column
rename_column
remove_column
add_index
remove_index
Use models
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
Associations
t.references :category # kinda same as t.integer :category_id
# Can have different types
t.references :category, polymorphic: true
Auto-Add/remove columns
$ rails generate migration RemovePartNumberFromProducts part_number:string
Indices
# Simple
add_index :suppliers, :name
# Unique
add_index :accounts, [:branch_id, :party_id], :unique => true
# Named (:name => ...)
add_index :accounts, [:branch_id, :party_id], :unique => true, :name => "by_branch_party"
# Length
add_index :accounts, :name, :name => ‘by_name’, :length => 10
add_index :accounts, [:name, :surname], :name => ‘by_name_surname’,
:length => {
:name => 10,
:surname => 15
}
# Sort order (no MySQL support)
add_index :accounts, [:branch_id, :party_id, :surname],
:order => {:branch_id => :desc, :part_id => :asc}
In console
Use ActiveRecord::Migration
.
ActiveRecord::Migration.add_index :posts, :slug
References
- http://apidock.com/rails/ActiveRecord/ConnectionAdapters/SchemaStatements/add_index