ActiveRecord has_one default value

Rails
1

My apologies if this is a dumb question, but I’ve searched around and
haven’t been able to come up with a solution.

Is there a way when specifying a has_one association to specify a
default value for an object if data is missing in the child table. For
instance:

class Student
has_one :university
end

if no university is associated to the student in the database, I would
like to automatically return an instance of NoUniverisity class instead
of it being set to nil. Similar to the NullObject refactoring described
in Fowler’s book.

Any ideas?

Thanks!
Jay

2

Jay Turpin wrote:

class Student
has_one :university
end

if no university is associated to the student in the database, I would
like to automatically return an instance of NoUniverisity class instead
of it being set to nil. Similar to the NullObject refactoring described
in Fowler’s book.

Warning - untested code:

class Student < ActiveRecord::Base
has_one :university

def university_or_default
old_university || NoUniversity.new
end

alias_method :old_university, :university
alias_method :university, :university_or_default

end

hth