Renaming original migration file in Rails after doing the rename_table_migration

Question

I happened to create a Query model in Rails and recently found out that this is one of the reserved words now..

I renamed the table using a new migration file and renamed all the files that were created (name of new model - Plot)

Question: is it OK to rename the original migration file (20111228212521_create_queries.rb) to 20111228212521_create_plots.rb)

and everything inside the old file:

class CreateQueries < ActiveRecord::Migration
 def change
   create_table :queries do |t|
    t.string :name
    t.text :content

    t.timestamps
    end
   end
 end

to

class CreatePlots < ActiveRecord::Migration
   def change
    create_table :plots do |t|
    t.string :name
    t.text :content

    t.timestamps
    end
   end
 end

??

I just don't want too many migration files and also worried that there may be some errors when I switch to production..

Answer 1

You can change the migration file name, but you have to perform a few steps:

1. rake db:rollback to the point that queries table is rolled back.

2. Now change the name of migration file, also the contents.

3. Change the name of any Model that may use the table.

4. rake db:migrate

Answer 2

The short answer is to just make another migration file.

Migration files are meant to keep track of each and every change to the database. So, you're encouraged to make small one-off changes in a separate file. I can't speak for your situation, but in my situation, when I make a mistake like this, I simply create a new migration file and don't check the old migration file into source control. This way the errant changes are only on my local db and don't get into prod/dev/staging.

Answer 3

Aside from rolling back, and especially useful for when you need to rename a migration from early on in production you can now in Rails 4 create a new migration to rename it.

1. $rails generate migration RenamesFooBarr

and then in the method of the new migration add

rename_table :old_migration_name, :new_migration name

like this:

class RenamesFooBar < ActiveRecord::Migration
   def change
       rename_table :old_foo_bar_name, :new_foo_bar_name
   end
end

This will effectively take care of all the indexes as well in the up and down since ActiveRecord recognizes the rename_table

source: http://api.rubyonrails.org/classes/ActiveRecord/Migration.html