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

You can just run the code directly out of the ruby file:

rails console
>> require "db/migrate/20090408054532_add_foos.rb"
>> AddFoos.new.up

Note: Very old versions of rails may require AddFoos.up rather than AddFoos.new.up.

An alternative way (without IRB) which relies on the fact that require returns an array of class names:

script/runner 'require("db/migrate/20090408054532_add_foos.rb").first.constantize.up'

Note that if you do this, it won't update the schema_migrations table, but it seems like that's what you want anyway.

Additionally, if it can't find the file you may need to use require("./db/..." or try require_relative depending on your working directory

Answer 2

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.

Answer 3

If you want to run a specific migration, do

$ rake db:migrate:up VERSION=20080906120000

If you want to run migrations multiple times, do

# use the STEP parameter if you need to go more than one version back
$ rake db:migrate:redo STEP=3

If you want to run a single migration multiple times, do

# this is super useful
$ rake db:migrate:redo VERSION=20080906120000

(you can find the version number in the filename of your migration)

---

Edit: You can also simply rename your migration file, Eg:

20151013131830_my_migration.rb -> 20151013131831_my_migration.rb

Then migrate normally, this will treat the migration as a new one (usefull if you want to migrate on a remote environment (such as staging) on which you have less control.

Edit 2: You can also just nuke the migration entry in the database. Eg:

rails_c> q = "delete from schema_migrations where version = '20151013131830'"
rails_c> ActiveRecord::Base.connection.execute(q)

rake db:migrate will then rerun the up method of the nuked migrations.

Answer 4

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 5

This are the steps to run again this migration file "20150927161307_create_users.rb"

1. Run the console mode. (rails c)

2. Copy and past the class which is in that file to the console.

   class CreateUsers < ActiveRecord::Migration
     def change
       create_table :users do |t|
         t.string :name
         t.string :email
         t.timestamps null: false   end
       end
     end
   end
   

3. Create an instance of the class CreateUsers: c1 = CreateUsers.new

4. Execute the method change of that instance: c1.change

Answer 6

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 7

If you're having trouble with paths you can use

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

Answer 8

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 9

Method 1 :

rake db:migrate:up VERSION=20080906120000

Method 2:

In Rails Console 1. Copy paste the migration class in console (say add_name_to_user.rb) 2. Then in console, type the following

Sharding.run_on_all_shards{AddNameToUser.up}

It is done!!

Answer 10

Please notice that instead of script/runner, you may have to use rails runner on new rails environments.

Answer 11

Looks like at least in the latest Rails release (5.2 at the time of writing) there is one more way of filtering the migrations being ran. One can pass a filter in a SCOPE environment variable which would be then used to select migration files.

Assuming you have two migration files 1_add_foos.rb and 2_add_foos.run_this_one.rb running

SCOPE=run_this_one rails db:migrate:up

will select and run only 2_add_foos.run_this_one.rb. Keep in mind that all migration files matching the scope will be ran.