Rails 3 belongs to validation


I want to restrict my users having more than one address.

Here are the definitions from my classes :

class User < ActiveRecord::Base
  has_one :address, dependent: :destroy
class Address < ActiveRecord::Base
  belongs_to :  user
validates :user, presence: true
  validate :
def user_association
unless Address.where(user_id: user.id).count == 0
      errors.add(:user_id, 'Only one address per user')

I’m creating my address from user model, like this :

def create_address_relation
a = Address.create(address_type: @type.to_s, user_id: id)
    self.address = a

However when I’m able to create two address objects for same user. (I’m using paranoia gem for soft deleting objects, not sure if that is relevant)

Any suggestion how to make validations work? except unique index on the db

validates :user, presence: true, uniqueness: true

Much easier than what you are trying to do.

Note that this will work in 99.999% of the time, 0.001% of the time you will get duplicate records in your database because of race conditions

Alternatively, if your user really is going to have only 1 address, then why isn’t the address_id field inside of the User model? (You would then have your User belong_to :address). Seems like a more appropriate model for what you are trying to do.


Thanks for the reply Jason (I almost wrote Json :), I really appreciate it.

validates :user, uniqueness: true

is simple way(When you specify association then it also check other model validation) also other way is add custom validation for check uniquness