Description
Given the following class definitions:
class Address
belongs_to :addressable, :polymorphic => true
end
class Person
has_many :addresses, :as => addressable
end
class Vendor < Person
end
and given the following code:
vendor = Vendor.create(...)
address = vendor.addresses.create(...)
p vendor
p address
will output:
#<Vendor id: 1, type: "Vendor" ...>
#<Address id: 1, addressable_id: 1, addressable_type: 'Person' ...>
Notice that addressable_type column is Person even though the actual class is Vendor.
Normally, this isn't a problem, however, it can have negative performance characteristics in certain circumstances. The most obvious one is that a join with persons or an extra query is required to find out the actual type of addressable.
This gem adds the ActiveRecord::Base.store_base_sti_class configuration option. It defaults to true for backwards compatibility. Setting it to false will alter ActiveRecord's behavior to store the actual class in polymorphic _type columns when STI is used.
In the example above, if the ActiveRecord::Base.store_base_sti_class is false, the output will be,
#<Vendor id: 1, type: "Vendor" ...>
#<Address id: 1, addressable_id: 1, addressable_type: 'Vendor' ...>
Usage
Add the following line to your Gemfile,
gem 'store_base_sti_class'
then bundle install. Once you have the gem installed, add the following to one of the initializers (or make a new one) in config/initializers,
ActiveRecord::Base.store_base_sti_class = false
When changing this behavior, you will have write a migration to update all of your existing _type columns accordingly. You may also need to change your application if it explicitly relies on the _type columns.
Notes
This gem incorporates work from:
It currently works with ActiveRecord 4.2.x through 6.0.x. If you need support for ActiveRecord 3.x, use a pre-1.0 version of the gem, or ActiveRecord < 4.2 use a pre-2.0 version of the gem.
Conflicts
This gem produces known conflicts with these other gems:
friendly_id
When using friendly_id >= 5.2.5 with the History module enabled, duplicate slugs will be generated for STI subclasses with the same sluggable identifier (ex: name). This will either cause saves to fail if you have the proper indexes in place, or will cause slug lookups to be non-deterministic, either of which is undesirable.
History
- https://github.com/rails/rails/issues/724
- https://github.com/rails/rails/issues/5441#issuecomment-4563865
- https://github.com/rails/rails/issues/4729#issuecomment-5729297
- https://github.com/rails/rails/issues/5441#issuecomment-264871920
Copyright
Copyright (c) 2011-2019 AppFolio, inc. See LICENSE.txt for further details.