CODEWITHSUNDEEP
rubydatabaseactiverecordrails-activerecord
Codejoy
Codejoy

Reputation: 3816

How to use belongs_to to the same model but for different columns (for meaning)

I have a model Group.

A group can have many addresses as locations. It has to have two kinds of other addresses for sure: one for a mailing address one for a billing address

So Address is a Model too, how do I have a belongs_to to the same model but with multiple ids?

i.e.

Group: mailing_address_id billing_address_id

The various locations is taken care of by a group_locations join table easy enough: id group_id address_id

But how do I use the belongs_to for the mailing_address_id and biling_address_id ??? normally it would be:

address_id (like it is in the join) but I need them to mean something.

this is an artifact of me wanting to seperate out the addresses into another table trying to keep the database relatively normalized I think it is called.

I also had a heck of a time building another kind of a join table that joins people in a group through the locations join table...but that is a diff topic I posted here:

https://stackoverflow.com/questions/31599419/building-a-migration-for-a-join-table-based-on-a-join-table-in-rails

Upvotes: 0

Views: 211

Answers (3)

Neil McGuigan
Neil McGuigan

Reputation: 48246

An address is just an address so should get its own table.

A person may be located at an address and use it in a role.

Two people could live at the same address. Both for home, and one for work. Therefore:

create table addresses (
  address_id int primary key,
  ...address info...
);

create table people (
  person_id int primary key,
  ...person info...
);

create table people_placements (
  person_id int references people(person_id),
  address_id int references addresses(address_id),
  address_role_id smallint references address_roles(address_role_id), /* definition elided */

  primary key (person_id, address_id, addres_role_id)
);

For a sales order you would reference the people_placements table for the billing party and address. Same for shipping party and address on your sales order line items.

Upvotes: 1

Horacio
Horacio

Reputation: 2965

you can try :foreign_key on your relation.

look for "4.1.2.5 :foreign_key" section on here

By convention, Rails assumes that the column used to hold the foreign key on this model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly

Upvotes: 1

adamliesko
adamliesko

Reputation: 1915

class Group < ActiveRecord::Base
  belongs_to: billing_address, class: 'Address', foreign_key: 'billing_address_id'
  belongs_to: mailing_address, class: 'Address', foreign_key: 'mailing_address_id'
end

Upvotes: 1

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