验证Rails 3.1模型中的数据

Question

My application use two varariables to take notes about product warranty start time and warranty end time;so in my view I use two dropdown menu to select start and end times. Now, I must sure that start time shouldn't greater than end time. In witch way can I model this restriction? I've tried with the following code in my model file:

  validates_numericality_of :warranty_end, :greater_than => :warranty_start 

but I've seen that it doesn't work! Any suggestions?

Answer 1

I don't think that you can use variables in validates like that, but you can create a custom validator like this

validates_numericality_of :warranty_end
validate :warranty_end_less_than_warranty_start

...

def warranty_end_less_than_warranty_start
  unless warranty_end > warranty_start
    errors.add :warranty_end, "must be before the warranty starting date"
  end
end

Answer 2

That should work (in 3.2 at least). From the docs at http://api.rubyonrails.org/classes/ActiveModel/Validations/HelperMethods.html :

validates_numericality_of :width, :less_than => Proc.new { |person| person.height } 
validates_numericality_of :width, :greater_than => :minimum_weight

Answer 3

Thank you Azolo now it's works! The only thing is that you delete "validates_numericality_of :warranty_end" statement, so working code for me is:

validate :warranty_end_less_than_warranty_start

...

def warranty_end_less_than_warranty_start
  unless warranty_end > warranty_start
    errors.add :warranty_end, "must be before the warranty starting date"
  end
end

Thank you all again