I have a new app on Rails 4.0.4 / Ruby 2.1.0. The first thing I did was adding Devise gem. When I want to run rake db:migrate, it just does nothing. No error, but the migration isn't executed.
Could you please help me what to do with this case? I can't find where is the problem.
Thank You! Petr
OK, so the problem was that Devise generator generated ".txt" file with migration instead of ".rb" file. Strange, but changing extension solved it.
I had the same problem as you Petr and I think I found out why. For some reason when I ran 'rails g devise User', it created a migration (db/migrate/[timestamp]_devise_create_users.rb). That's what it suppose to be, but upon further examination, the migration was missing the '.rb' at the end. So it looked like (db/migrate/[timestamp]_devise_create_users). When I added the .rb at the end, and ran 'rake db:migrate' it worked like a charm. I don't know why rails didn't attach the '.rb' at the end. Hope that helps.
After you install devise gem, you have to do the following
rails generate devise:install
The generator will install an initializer which describes ALL Devise's configuration options and you MUST take a look at it. When you are done, you are ready to add Devise to any of your models using the generator
rails generate devise <model>
This is the step that generates the migration. For eg, If you want to add devise to user model, you should do
rails generate devise User
So it will generate a migration to add devise related columns to users table
来源：https://stackoverflow.com/questions/22582772/rake-dbmigrate-doesnt-work-rails-4-0-4