Question

:inclusion => {:in => r = (1..15), :min => r.first, :max => r.last}

This is working code I have. The thing I wanted to make dynamic is the “15” part, e.g

:inclusion => {:in => r = (1..Vehicle.max_passengers), :min => r.first, :max => r.last}

I have defined the following class method:

def self.max_passengers
   15
end  

Of course it didn’t work. I’ve tried using Procs and lambdas, but It didn’t work properly for me. 🙁
Can someone help me with this one – is it possible ?

Answer 1

You’re looking for a custom validation method:

ActiveRecord::Base.class_eval do
  def self.validates_max_passenger(attr_name, r)
    validates attr_name, :inclusion => { :in => r, :min => r.first, :max => r.last } }
  end
end

# later in your class of choice:      
validates_max_passenger :passengers, 1..5

Or, you can try the following with lambda

def self.max_passengers
   1..15
end  


validates :attrib, :inclusion => {:in => lambda { |obj| ClassName.max_passengers } }

Note that you won’t need the min/max if you’re using :in on range.