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Modifies ActiveRecord 3.0.5+ with the ability to store the actual class (instead of the base class) in polymorphic _type columns when using STI
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Appraisals jk - add more rails version appraisals Apr 6, 2016

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Given the following class definitions,

class Address
  belongs_to :addressable, :polymorphic => true

class Person
  has_many :addresses, :as => addressable

class Vendor < Person

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 characteristic 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 add ActiveRecord::Base.store_base_sti_class configuration option. It defaults to true for backwards compatibility. Setting it 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' ...>


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.


This gem incorporates work from:

It currently works with ActiveRecord 3.0.5 through 4.2.x.


Copyright (c) 2011-2015 AppFolio, inc. See LICENSE.txt for further details.

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