Question

Say I have an assets model that contains two columns:

Assets
    ownership:string
    lease_id:integer   # My Lease Object

So ownership can either be “OWN” or “LEASE”.

Now, I only want to allow a lease_id if ownership is LEASE and if ownership happens to be LEASE then I want to require a lease object.

How can this be done in Rails 3.2.2?

Answer 1

You can add optional validations based on a method which returns true/false. Keep in mind that this will only enforce that a lease_id is present when ownership == "LEASE". This will not restrict a lease_id from being added in any case.

class Asset < ActiveRecord::Base
  validates :lease_id, presence: { :if => :lease? }

  def lease?
    self.ownership == "LEASE"
  end
end

If you want to restrict a lease_id altogether, you can use a callback to remove the property before the object is saved to the DB.

class Asset < ActiveRecord::Base
  before_create :restrict_lease_id

  def restrict_lease_id
    lease_id = nil if self.ownership == "LEASE"
  end
end