Rails 4 - Validates uniqueness with has_many through

Question

I have these three models:

User:

class User < ActiveRecord::Base
  validates :name, presence: true
  validates :surname, presence: true
  validates :email, presence: true, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i }

  has_many :permissions, dependent: :destroy
  has_many :stores, through: :permissions
end

Store:

class Store < ActiveRecord::Base
  validates :name, presence: true
  validates :description, presence: true

  has_many :permissions
  has_many :users, through: :permissions
end

Permission:

class Permission < ActiveRecord::Base
  belongs_to :user
  belongs_to :store
end

How can i validate the uniqueness of the user.email based on the store.id?

Don't you validate email uniqueness in user model? Shouldn't email be a unique identifier for users? — wesley6j, May 31 '17 at 11:33
I need to allow users to be able to subscribe to multiple stores with the same email. — Mattia M., May 31 '17 at 11:36
It makes more sense that a user can subscribe to multiple stores without register multiple accounts? — wesley6j, May 31 '17 at 11:38

score 2 · Accepted Answer · answered May 31 '17 at 11:38

2

You don't.

You should validate the uniqueness of the users email in User. And validate the uniqueness of the user_id and store_id in Permission.

class User < ApplicationRecord
  # ...
  validates_uniqueness_of :email
end

class Permission < ApplicationRecord
  validates_uniqueness_of :user_id, scope: 'store_id'
end

This allows a user to have permissions for multiple stores - but does not allow duplicates. In general when linking records together use id's - not something like emails.

answered May 31 '17 at 11:38

max

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As @wesley6j allready stated - it makes no sense that users should be able to create multiple accounts with the same email - you allready have a many to many assocation that will allow a single user account to be linked to any number of stores. – max May 31 '17 at 11:43

Rails 4 - Validates uniqueness with has_many through

1 Answers1