Rails Conditional Validation

Question

So I have two models here:

class Screen < ActiveRecord::Base
  belongs_to :user
  validates :screen_size, :numericality =>{:less_than_or_equal_to =>         


        

Answer 1

You passed in a string to the :if executable proc/function parameter. When this is a string, it tries to find a function with that name. What you actually want is an anonymous function here using a lambda.

class Screen < ActiveRecord::Base
  belongs_to :user
  validates :screen_size, :numericality => {:less_than_or_equal_to =>100, :greater_than_or_equal_to => 0}, :if => lambda {|s| s.user.access == 1 }
end

class User < ActiveRecord::Base
  has_many :screens
  attr_accessible :access
end

Answer 2

change:

:if => "user.access==1"

with:

:if => lambda { |screen| screen.user.try(:access) ==1 }

Because:

• you need to pass a function to evaluate condition on the fly

• if your screen doesn't have any user, a mere screen.user.access would throw an exception