Question

When I ran bundle exec rake db:test:prepare I got the following:

rake aborted!
Multiple migrations have the name CreateMicroposts

To check the status of my migration files, I ran

rake db:migrate:status

And got:

Status Migration ID Migration Name
——- ————— —————–

up 20120616205407 Create users

up 20120622103932 Add index to users email

up 20120622114559 Add password digest to users

up 20120628095820 Add remember token to users

up 20120704123654 Add admin to users

down 20120706103254 Create microposts

up 20120707073410 Create microposts

As you can see, I have two migration files with the exact same names and the exact same code in them. It’s only their statuses differ, i.e. Up and Down.

What does Up and Down signify?

And which one can I delete, if I have to?

Answer 1

The problem is that you have two different migration files containing the header

class CreateMicroposts< ActiveRecord::Migration

rake db:migrate:status does not check the status of your migration files. It tells you what migrations will be applied if you run rake db:migrate. The up/down labels are pretty much self-explanatory: it tells you whether the migration will be applied via the up method or the down method. The up method is ran when you migrate and the down when you rollback a migration. You can make some further reading about Rails migrations here.