ruby on rails - Validating min and max length of a phone number according to select of country code -

i have phone number field country code in drop-down, want validate max length validation according selection of country code in drop-down.

profile.rb

validates_length_of :phone, :minimum => 10, :maximum => 10 if country_code = 91 

you can't that; if evaluate @ class definition, not @ validation time. either need use :if option:

validates_length_of :phone, :minimum => 10, :maximum => 10,     :if => proc.new { |x| x.country_code == 91 } 

or need use custom validator, like:

phone_length_limits_by_country_code = {   91 => [10, 10] } def phone_number_is_correct_according_to_country_code   min, max = *phone_length_limits_by_country_code[country_code]   if phone.length < min || phone.length > max     errors.add(:phone, "must between #{min} , #{max} characters")   end end validate :phone_number_is_correct_according_to_country_code 

(disclaimer: untested code)