How to protect a user password with bcrypt and mongoid - mongoid

Question

I've just started out using MongoDB and, in particular, Mongoid.
naturally I'd like to ensure my User's passwords are kept nice and secure, and previously I'd have done this with ActiveRecord and used bcrypt. I'm looking for a nice, clean, secure, simple way to implement the same sort of thing using Mongoid.
I've taken a look at mongoid-encryptor but I've not quite got my head around how to use it.
Assume my simplified User looks like this, as per the example in mongoid-encryptor's Readme file.
class User
include Mongoid::Document
include Mongoid::Encryptor
field :name
field :password
encrypts :password
end
And in my WebApp (using Sinatra in this case) I'd define a helper such as
def login (name, cleartxtpass)
return User.where(name: name, password: cleartxtpass).first
end
How do I get it to use bcrypt?
Is there any pre-processing I need to do with cleartxtpass or will Mongoid::Encryptor just handle that? It's not clear from the docs.

Answer 1

Okay well after some digging I decided to not bother using Mongoid::Encryptor but to stick to the tried and tested way I used to do these things when using ActiveRecord.
So now my User looks like
class User
include Mongoid::Document
field :name, type: String
field :password_hash, type: String
index({name: 1}, {unique: true, name: 'user_name_index'})
include BCrypt
def password
#password ||= Password.new(password_hash)
end
def password=(new_password)
#password = Password.create(new_password)
self.password_hash = #password
end
end
and my authenticate helper method looks like
def auth_user(username, password)
user = User.where(name: username).first
return user if user && user.password == password
return nil
end
That works a treat.

Answer 2

The simply way to do it is:
class User
include Mongoid::Document
include ActiveModel::SecurePassword
field :name, type: String
field :password_digest, type: String
has_secure_password
end