What to do if nofile is displayed when deleting a migration

First, find out the ID of the migration file you want to delete.

$ rake db:migrate:status

and understand the current situation.

database: petipeti_development

 Status   Migration ID    Migration Name
--------------------------------------------------
  down    2017072605442   Create gambles0
   up     20170726054542  ********** NO FILE **********
  down    20170726074346  Create gambles

In this case, this is the file you want to delete.

up     20170726054542  ********** NO FILE **********

Since there is no file, create a migration file anyway. The format should be migration_id_tmp.rb.

20170726054542_tmp.rb

Then, write the contents below in the 20170726054542_tmp.rb you just created.

class Tmp < ActiveRecord::Migration
  def change
  end
end

In the case of rails5

class Tmp < ActiveRecord::Migration[5.0]
  def change
  end
end

If you don’t do this, you’ll be at the terminal.

Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:
  class Tmp < ActiveRecord::Migration[4.2]

and an error is displayed.

Check the status of the migration when you have completed the work up to this point.

$ rake db:migrate:status
database: petipeti_development

 Status   Migration ID    Migration Name
--------------------------------------------------
  down    2017072605442   Create gambles0
   up     20170726054542  Tmp
  down    20170726074346  Create gambles

You can see that the guy who was no file earlier has changed to Tmp.

Next, let’s down this migration file.

$ rake db:migrate:down VERSION=20170726054542

Check to see if you did it correctly.

$ rake db:migrate:status
database: petipeti_development

 Status   Migration ID    Migration Name
--------------------------------------------------
  down    2017072605442   Create gambles0
  down    20170726054542  Tmp
  down    20170726074346  Create gambles

After confirming the down, delete the migration file.

$ rails destroy migration Tmp
database: petipeti_development

 Status   Migration ID    Migration Name
--------------------------------------------------
  down    2017072605442   Create gambles0
  down    20170726074346  Create gambles

It worked perfectly.