Dumb question

[brent brent]

Folks
Can a model just have a belongs_to only? or do you have to have a
belongs_to and a has_many or has_one on the other model?

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[Agis A.]

Of course you can. 

[Greg Akins]

On Sun, May 27, 2012 at 1:34 PM, brent brent <li...@ruby-forum.com> wrote:
> Folks
>  Can a model just have a belongs_to only? or do you have to have a
> belongs_to and a has_many or has_one on the other model?
>
> --

http://guides.rubyonrails.org/association_basics.html#the-belongs_to-association

--
Greg Akins
http://twitter.com/akinsgre

[Rafael Magaña]

What belongs_to and their counterparts does is create a method to access an existing relationship, the actual relationship is made in the tables themselves by adding model_id columns, for instance:

    class User < ActiveRecord::Base

        has_one :address

    end

    class Address < ActiveRecord::Base

        belongs_to :user

    end

    # Shows the address whose addresses.user_id = users.id

    User.last.address

    # Shows the user whose users.id = addresses.user_id

    Address.last.user

If you don't need to access the relationship in the Address model just delete `belongs_to :user`:

    

    class Address < ActiveRecord::Base

    end

 

    User.last.address # Shows address

    Address.last.user # NoMethodError: undefined method `user'