ruby on rails - Mongoid many-to-many, is this normal? -

here models:

class user   include mongoid::document   include mongoid::timestamps   references_many :roles, :stored_as => :array, :inverse_of => :users   ... end  class role   include mongoid::document    field :name, :type => string    references_many :users, :stored_as => :array, :inverse_of => :roles   ... end 

i first create roles via seed, rake db:seed. seed file contains:

puts '*** add default roles' [   { :name  => 'user' },   { :name  => 'artist' } ].each |h|   role.create(h) end 

the roles created successfully. however, when add role user, do:

foobar = user.first foobar.roles.create(:name => 'user')  

i notice 2 things:

1) adds role reference in user collection.

2) creates 3rd role in role collection.

this kind of strange because have 3 roles: user, artist , user. 2nd user collection has user_ids reference contains foobar's id.

is normal?

i think rather want do:

foobar = user.first foobar.roles << role.find(:name => 'user') foobar.save 

this way role object not created, reference added existing record.