Need a piece of code #rails 3 (custom validations)

Question

I want to show an error message like "date of joining is Invalid" if the "date of joining" is before the "date of birth"(it doesnt happen in real.. but i want it).

Please suggest me with a piece of code.

Answer 1

i think you have a user model whith date_of_birth attribute , date of joining is the date when you save your user, and Active Record create automatically for you an attribute "created_at" for each object you save in database.

so you can consider "created_at" like date_of_join.

the next step is to add a validate method to your user model like this :

class User < ActiveRecord::Base
 #attr_accessible :date_of_birth, ( etc ...... )
 #.....
 #.....
 validate  :date_of_join_must_be_great_than_birth
 #.....
 #.....
 private

     def date_of_join_must_be_great_than_birth
       errors.add(:date_of_birth, "date of birth is greater than date of joining" ) unless date_of_birth < created_at
     end

 end

each time you save or you update your user, validate method is invoked

you can also learn about filter methods in rails , i hope this can help you

Answer 2

You can do this by many ways.Just refer this tutorial

http://guides.rubyonrails.org/active_record_validations_callbacks.html