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Rails Migration - Cheatsheet

Rails Migration

http://guides.rubyonrails.org/migrations.html

Migrations methods:

  • add_column
  • add_index
  • change_column
  • change_table
  • create_table
  • drop_table
  • remove_column
  • remove_index
  • rename_column

Basic format YYYYMMDDHHMMSS_create_products.rb

Supported types

  • :binary
  • :boolean
  • :date
  • :datetime
  • :decimal
  • :float
  • :integer
  • :primary_key
  • :string
  • :text
  • :time
  • :timestamp especial type:
  • :references

create_table

Commands to create migrations

$ rails generate model Product name:string description:text
$ rails generate migration AddPartNumberToProducts part_number:string
$ rails generate migration RemovePartNumberFromProducts part_number:string
$ rails generate migration AddDetailsToProducts part_number:string price:decimal

change_table

  • add_column
  • add_index
  • add_timestamps
  • create_table
  • remove_timestamps
  • rename_column
  • rename_index
  • rename_table

Running Migrations

$ rake db:migrate VERSION=20080906120000
$ rake db:rollback
$ rake db:rollback STEP=3
$ rake db:migrate:redo STEP=3
$ rake db:reset  #drop database and recreate it
$ rake db:migrate:up VERSION=20080906120000

Migrations commands

rake db:migrate         # Migrate the database (options: VERSION=x, VERBOSE=false).
rake db:migrate:status  # Display status of migrations
rake db:rollback        # Rolls the schema back to the previous version (specify steps w/ STEP=n).
rake db:test:prepare    # Rebuild it from scratch according to the specs defined in the development database

more Database commands (rake -T db)

rake db:create          # Create the database from config/database.yml for the current Rails.env (use db:create:all to create all dbs in t...
rake db:drop            # Drops the database for the current Rails.env (use db:drop:all to drop all databases)
rake db:fixtures:load   # Load fixtures into the current environment's database.
rake db:schema:dump     # Create a db/schema.rb file that can be portably used against any DB supported by AR
rake db:schema:load     # Load a schema.rb file into the database
rake db:seed            # Load the seed data from db/seeds.rb
rake db:setup           # Create the database, load the schema, and initialize with the seed data (use db:reset to also drop the db first)
rake db:structure:dump  # Dump the database structure to db/structure.sql. Specify another file with DB_STRUCTURE=db/my_structure.sql
rake db:version         # Retrieves the current schema version number
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