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There is a setup that you need to do before you can use doorkeeper.

Step 1.
Go to config/initializers/doorkeeper.rb and configure
resource_owner_authenticator block.

Step 2.
Choose the ORM:

If you want to use ActiveRecord run:

  rails generate doorkeeper:migration

And run

  rake db:migrate

If you want to use Mongoid, configure the orm in initializers/doorkeeper.rb:

# Mongoid
Doorkeeper.configure do
  orm :mongoid
end

If you want to use MongoMapper, configure the orm in
initializers/doorkeeper.rb:

# MongoMapper
Doorkeeper.configure do
  orm :mongo_mapper
end

And run

  rails generate doorkeeper:mongo_mapper:indexes
  rake db:index

Step 3.
That's it, that's all. Enjoy!

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