Question

I have Users Bands and Codes.

A user creates a code and that code has a user_id and a band_id.

I have a before save callback generating the code.

before_create :generate_code

  private
    def generate_code      
      self.code = SecureRandom.hex(3)
    end

I need to add a check, if code exists with user_id and band_id, return false

That way a user will only have one code per band

thoughts?

Answer 1

if you want to keep generating until you get a valid code, try:

def generate_code
  begin
    self.code = SecureRandom.hex(3)
  end while User.exists?(:code => self[:code])
end

if you just want to try one code, and return false, try:

def generate_code
  self.code = SecureRandom.hex(3)
  return false if User.exists?(:code => self[:code])
end

Note: change “User” to whatever your relation you’re checking the collision in 🙂

Alternatively, you could just try validates :code, :uniqueness => true or something similar 🙂