problem with passing booleans to update_attributes

Question

I've got the following Model:

class GuestCatering < ActiveRecord::Base

  # Validation
  validates :name, :presence => true
  validates :order_number, :presence => true
  validates :orderable, :presence => true

end

But when I'll try to update an existing GuestCatering with the following code:

guest_catering.update_attributes(:orderable => false)

The guest catering variable is a valid GuestCatering object. The guest_catering object has errors after the update, like that:

<{[:orderable, ["can't be blank"]]=>nil}>

But when i pass a orderable => true, everything is fine and no errors.

What's wrong here, why can't i set orderable to false?

Answer 1

Your model is actually behaving exactly as you told it to, through your use of validates :orderable, :presence => true

There's little point validating the presence of a boolean flag - it's going to be true, nil or false - and in Ruby world, nil and false have the same semantic value when it comes to boolean logic.

Internally, validates :presence relies on the value of the attribute being checked to return false when blank? is called. And, in Rails (with ActiveSupport), false.blank? evaluates as true - which means that your field is failing the validation.

Simply remove that validation and everything will work as expected.

Answer 2

Like Dan Cheail already said in his answer, a nil and false boolean is semantically the same thing.

But, if you really need to validate it (not allowing nil), you can always do :

validates_inclusion_of :orderable, :in => [true, false]