Delegation

By default, low_card_tables makes all attributes of your low-card table show up as attributes on the referring table.

These attributes are defined as methods in a dynamically-created module called, for a model User, User::LowCardDynamicMethods. This method is included into your module. As a result, you can override these methods in your model, and that'll work just fine; you can also call super in them, and it will call the appropriate low-card method.

No matter what, you can always access these attributes through the association name — for example, my_user.status.gender will always work, as will my_user.status.gender = 'female'.

Controlling What Gets Delegated

If you don't like full delegation, you have several options:

class User < ActiveRecord::Base
  has_low_card_table :status, :delegate => nil
end

This will turn off delegation entirely. Your only access to the low-card attributes is via (e.g.) my_user.status.gender.

class User < ActiveRecord::Base
  has_low_card_table :status, :delegate => [ :deleted, :gender ]
end

This will delegate only the deleted and gender attributes. Other attributes must be referred to via the association.

class User < ActiveRecord::Base
  has_low_card_table :status, :delegate => { :except => [ :deleted, :gender ] }
end

This will delegate everything except the deleted and gender attributes.

class User < ActiveRecord::Base
  has_low_card_table :status, :delegate => [ :deleted, :gender ]
end

The Delegation Prefix

You can also change the delegation prefix:

class User < ActiveRecord::Base
  has_low_card_table :status, :prefix => true
end

Now these methods are called my_user.status_gender, my_user.status_deleted, and so on.

class User < ActiveRecord::Base
  has_low_card_table :status, :prefix => 'foo'
end

Now these methods are called my_user.foo_gender, my_user.foo_deleted, and so on.

Collisions

If you refer to multiple low-card tables from a single referring table, it's possible that there is more than one low-card table that defines a given attribute. In this case, the last definition wins. For example, if both user_statuses and user_photo_statuses have an attribute deleted:

class User < ActiveRecord::Base
  has_low_card_table :status
  has_low_card_table :photo_status
end

Now my_user.deleted will refer to my_user.photo_status.deleted, and you can only access the status from user_statuses as my_user.status.deleted. To avoid this situation, use :prefix.

(This can also happen in the rare case where you refer to a single low-card table multiple times from the same referring table — for example, if you wanted to track user_status_id and old_user_status_id.)