self referential model?

is it possible to have a model be belong to itself?

say i have a category, and the category can be a subcategory of another
category (or it might be a parent category)..

is this possible, and does it make sense?

something like:

class Category < ActiveRecord::Base
   has_many: categories
end

i kinda think it would make more sense to use a subcategory model.. but
the system i am deriving from (which was written in php) is combining
the models..

thanks!

Sergio Ruiz wrote:

is it possible to have a model be belong to itself?

say i have a category, and the category can be a subcategory of another
category (or it might be a parent category)..

http://github.com/collectiveidea/awesome_nested_set/

is this possible, and does it make sense?

Yes, it makes sense.

something like:

class Category < ActiveRecord::Base
   has_many: categories
end

i kinda think it would make more sense to use a subcategory model.. but
the system i am deriving from (which was written in php) is combining
the models..

No. As you'll see from the above plugin using one model does make more
sense.

you can read rails guides.
http://guides.rubyonrails.org/association_basics.html#polymorphic-associations

class Employee < ActiveRecord::Base
  has_many :subordinates, :class_name => "Employee", :foreign_key =>
"manager_id"
  belongs_to :manager, :class_name => "Employee"
end

With this setup, you can retrieve @employee.subordinates and @employee.manager.