Conditional validations in rails

By default, validations will take place every time the model is saved. Sometimes you only want a validation to happen when certain conditions are met. See how to do that in this episode.

# models/user.rb
validates_presence_of :password, :if => :should_validate_password?
validates_presence_of :country
validates_presence_of :state, :if => :in_us?
attr_accessor :updating_password

def in_us?
 country == 'US'
end

def should_validate_password?
 updating_password || new_record?
end

# in controller
@user.updating_password = true
@user.save

# or...
@user.save(false)