rails validations - passing values to options

Question

My last question https://stackoverflow.com/questions/13112897/rails-begginer-validations was closed as too localised, so I'll try to be more generic.

Is it possible to pass value from current record (or from session) to validation option?

This works:

validates :name, :length => { :minimum => 2 }

But, if I have field "minlength" in my model, and want to validate length of the "name" against the value in "minlength" field - how can I do that?

Those examples don't work.

validates :name, :length => { :minimum => self.minlength }
validates :name, :length => { :minimum => :minlength }
validates :name, :length => { :minimum => session_variable_with_minlength_value }

Answer 1

you can pass custom validation for that :

for example

validate:name_length

def name_length
  if self.name.size < self.minlength.to_i 
    errors[:base] << "whatever error message you want to display here"
  end
end