Run a single migration file

Question

Is there an easy way to run a single migration? I don\'t want to migrate to a certain version I just want to run a specific one.

Answer 1

As of rails 5 you can also use rails instead of rake

Rails 3 - 4

# < rails-5.0
rake db:migrate:up VERSION=20160920130051

Rails 5

# >= rails-5.0
rake db:migrate:up VERSION=20160920130051

# or

rails db:migrate:up VERSION=20160920130051

Answer 2

If you're having trouble with paths you can use

require Rails.root + 'db/migrate/20090408054532_add_foos.rb'

Answer 3

If you've implemented a change method like this:

class AddPartNumberToProducts < ActiveRecord::Migration
  def change
    add_column :products, :part_number, :string
  end
end

You can create an instance of the migration and run migrate(:up) or migrate(:down) on an instance, like this:

$ rails console
>> require "db/migrate/20090408054532_add_part_number_to_products.rb"
>> AddPartNumberToProducts.new.migrate(:down)

Answer 4

If you want to run it from console, this is what you are looking for:

$ rails console
irb(main)> require "#{Rails.root.to_s}/db/migrate/XXXXX_my_migration.rb"
irb(main)> AddFoo.migrate(:up)

I tried the other answers, but requiring without Rails.root didnt work for me.

Also, .migrate(:up) part forces the migration to rerun regardless if it has already run or not. This is useful for when you already ran a migration, have kinda undone it by messing around with the db and want a quick solution to have it up again.

Answer 5

Assuming fairly recent version of Rails you can always run:

rake db:migrate:up VERSION=20090408054532

Where version is the timestamp in the filename of the migration.

Edit: At some point over the last 8 years (I'm not sure what version) Rails added checks that prevent this from running if it has already been run. This is indicated by an entry in the schema_migrations table. To re-run it, simply execute rake db:migrate:redo VERSION=20090408054532 instead.