class Warden::Manager

def serialize_from_session(scope = nil, &block)

:api: public

Warden::Manager.serialize_from_session(:admin) { |id| AdminUser.get(id) }
# With Scope:
Warden::Manager.serialize_from_session{ |id| User.get(id) }
Example:

You can supply different methods of de-serialization for different scopes by passing a scope symbol
Use the results of user_session_key to reconstitute the user from the session on requests after the initial login
Reconstitutes the user from the session. 
def serialize_from_session(scope = nil, &block)
  method_name = scope.nil? ? :deserialize : "#{scope}_deserialize"
  if Warden::SessionSerializer.method_defined? method_name
    Warden::SessionSerializer.send :remove_method, method_name
  end
  Warden::SessionSerializer.send :define_method, method_name, &block
end