How to make helpers for models - ruby-on-rails

Question

I have this private method in my User model
class User < ActiveRecord::Base
attr_accessible :email, :fullname, :password, :username
has_secure_password
before_create { generate_token(:remember_token) }
.
.
private
def generate_token(col)
begin
self[col] = SecureRandom.urlsafe_base64
end while User.exists?(col => self[col])
end
end
How can i make generate_token available In other models?
Thanks

Answer 1

many options here are some:
use a plain, simple ruby module.
module TokenRememberable
private
def generate_token(col)
begin
self[col] = SecureRandom.urlsafe_base64
end while User.exists?(col => self[col])
end
end
class User < ActiveRecord::Base
include TokenRememberable
before_create { generate_token(:remember_token) }
end
for more complex functionnality, use ActiveSupport::Concern :
module TokenRememberable
extend ActiveSupport::Concern
# thanks to Concern, this block wil be evaluated
# in the context of the including class
included do
before_create { generate_token(:remember_token) }
end
private
def generate_token(col)
begin
self[col] = SecureRandom.urlsafe_base64
end while self.class.exists?(col => self[col])
end
end
class User < ActiveRecord::Base
include TokenRememberable
end
extract the functionnality in a dedicated class, and possibly use composition
# we only need a class method here, but you can also build
# full-fledged objects as you need
class TokenGenerator
def self.generate_token
# your generation logic here
end
end
class User
def after_initialize
#token_generator = TokenGenerator # or TokenGenerator.new( self ), for instance
end
attr_reader :token_generator
delegate :generate_token, to: :token_generator # optionnaly use delegation
end
NOTE :
this is not really a rails issue, more a Ruby one. You should document yourself more on the language you are using... Modules are a very common idiom. I can give you some good reference books if you need

Answer 2

a few approaches:
slightly dependent:
do:
class User < ActiveRecord::Base
before_create { User::Helpers.new(self).generate_token(:remember_token) }
class Helpers < Struct.new(:user)
def generate_token(col)
begin
user.send("#{col}=", SecureRandom.urlsafe_base64)
end while User.exists?(col => user.send(col))
end
end
end
independent: don't pass the user object to the class, just make the method render a random token and assign it from the model.