Rails validate uniqueness only if conditional

Question

I have a Question class:

class Question < ActiveRecord::Base
  attr_accessible :user_id, :created_on

  validates_uniqueness_of :created_on, :scope =>          


        

Answer 1

Just add a condition to the validates_uniqueness_of call.

validates_uniqueness_of :created_on, scope: :user_id, unless: :has_posted?
def has_posted
  exists.where(user_id: user_id).where("created_at >= ?", Time.zone.now.beginning_of_day)
end

But even better, just create a custom validation:

validate :has_not_posted
def has_not_posted
  posted = exists.where(user: user).where("DATE(created_at) = DATE(?)", Time.now)
  errors.add(:base, "Error message") if posted
end