Rails - How to validate a field only if a another field has a certain value? -

Rails - How to validate a field only if a another field has a certain value? -

i'm pretty new rails , came across problem wasn't able solve friend google :)

in form have select 3 values: apple, banana , cherry. if take apple select hide select- , text-field javascript, because when apple chosen, there no need fill in these other 2 fields anymore.

so have problem validating form when it's submitted. i've found similar problems illustration in case of "only validate field if blank."

this problem solved this:

validates_presence_of :mobile_number, :unless => :home_phone?

so i've tried first thing popped mind:

validates_presence_of :state, :granted_at, :if => :type != 1

but when run it, error:

undefined method `validate' true:trueclass

so didn't find out how can access values object created... give thanks in advance help , hope question isn't obvious sounds :-)

because executable code need wrap in lambda or proc object so:

validates_presence_of :state, :granted_at, :if => lambda { |o| o.type != 1 } # alternatively: # :if => proc.new { |o| o.type != 1 }

ruby-on-rails ruby-on-rails-3 validation models