I have an Account model and a User model:
class Account < ActiveRecord::Base has_many :users end class User < ActiveRecord::Base belongs_to :account end
Users belong to an account and an account have a user maximum (different for each account). But how do I validate that this maximum have not been reached when adding new users to an account?
First I tried to add a validation on the user:
class User < ActiveRecord::Base belongs_to :account validate :validate_max_users_have_not_been_reached def validate_max_users_have_not_been_reached return unless account_id_changed? # nothing to validate errors.add_to_base("can not be added to this account since its user maximum have been reached") unless account.users.count < account.maximum_amount_of_users end end
But this only works if I'm adding one user at a time.
If I add multiple users via
@account.update_attributes(:users_attributes => ...) it just goes directly through even if there is only room for one more user.
Just to clarify: The current validation method validates that
account.users.count is less than
account.maximum_amount_of_users. So say for instance that
account.users.count is 9 and
account.maximum_amount_of_users is 10, then the validation will pass because 9 < 10.
The problem is that the count returned from
account.users.count will not increase until all the users have been written to the database. This means adding multiple users at the same time will pass validations since the user count will be the same until after they are all validated.
So as askegg points out, should I add validation to the Account model as well? And how should that be done?
If you call
account.users.countit will also include users which have been built but not saved to the database.
HOWEVER this will not fully solve your problem. When you call
accountin a user it is not returning the same account instance that
@accountis pointing to so it does not know about the new users. I believe this will be "fixed" in Rails 3, but in the meantime I can think of a couple solutions.
If you are saving the account the same time you are adding users (which I assume so since you are calling
update_attributes) then the validation can go in there.
I'm not sure how you are saving the associated models, but if account validation fails they should not be saved.
The other solution is to reset the
user.accountinstance to self when updating user attributes. You could do this in the users_attributes setter method.
This way user's account will point to the same account instance so
account.users.sizeshould return the amount. In this case you would keep the validations in the user model.
It's a tricky problem but hopefully this gave you some ideas on how to solve it.