#2756 [patch] The polymorphic type field should be subclass name instead of base class name when using polymorphic association with single table inheritance - Ruby on Rails

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#2756 ✓stale

[patch] The polymorphic type field should be subclass name instead of base class name when using polymorphic association with single table inheritance

Reported by tsechingho | June 4th, 2009 @ 11:57 AM | in 3.x

For a long time it was a problem for people wanting to use polymorphic association with single table inheritance.
The solution was pointed out (ticket #547, http://dev.rubyonrails.org/ticket/6485, http://dev.rubyonrails.org/ticket/8841).

For example, we should use @owner.class.name.to_s rather than @owner.class.base_class.name.to_s for the record["#{@reflection.options[:as]}_type"] attribute in set_belongs_to_association_for method in active_record/associations/association_proxy.rb.
Beside that, we should consider the namespace problem (full class name or demodulized name) mentioned in ticket #465. So @owner.class.sti_name.to_s is more proper than @owner.class.name.to_s.

When we look at the whole active record library, this wrong taken causes many place should be fixed (association_preload.rb, associations.rb, association_proxy.rb, belongs_to_polymorphic_association.rb, has_many_association.rb, has_many_through_association.rb, has_one_association.rb and autosave_association.rb).

I prepared a patch to resolve these situations. This patch should also fix problems mentioned in ticket #2435, #2594, #2601.
The related test cases were fixed too (join_model_test.rb, eager_test.rb, eager_load_includes_full_sti_class_test.rb).
So there were no problems even if we have complicated models like 'Post', 'Tag' and 'Tagging' in test/models.

class Post < ActiveRecord::Base
  has_many :taggings, :as => :taggable

  has_many :tags, :through => :taggings
  has_many :funky_tags, :through => :taggings, :source => :tag
  has_many :super_tags, :through => :taggings

  has_one :tagging, :as => :taggable

  has_many :invalid_taggings, :as => :taggable, :class_name => "Tagging", :conditions => 'taggings.id < 0'
  has_many :invalid_tags, :through => :invalid_taggings, :source => :tag
end

class Tagging < ActiveRecord::Base
  belongs_to :tag, :include => :tagging
  belongs_to :super_tag,   :class_name => 'Tag', :foreign_key => 'super_tag_id'
  belongs_to :invalid_tag, :class_name => 'Tag', :foreign_key => 'tag_id'
  belongs_to :taggable, :polymorphic => true, :counter_cache => true
end

class Tag < ActiveRecord::Base
  has_many :taggings
  has_many :taggables, :through => :taggings
  has_one  :tagging

  has_many :tagged_posts, :through => :taggings, :source => :taggable, :source_type => 'Post'
end

The remain question is this patch will cause problems to plugins which also use 'base_class.name', like 'has_many_polymorphs' as I know.
Maybe more test cases should be added for this path, but I feel that this problem should be solved before rails 3.0.

polymorphic_and_sti_fix.diff 23.6 KB

Comments and changes to this ticket

Pratik August 9th, 2009 @ 10:01 PM
- Assigned user set to “José Valim”
José Valim August 9th, 2009 @ 10:08 PM
- Assigned user changed from “José Valim” to “Pratik”
Jeremy Kemper May 4th, 2010 @ 06:48 PM
- Milestone changed from “2.x” to “3.x”
[bulk edit]
Dan Pickett May 9th, 2010 @ 07:27 PM
- Tag changed from “2.3.2, activerecord, associations, association_preload, association_proxy, autosave_association, belongs_to_polymorphic_association, has_many_association, has_many_through_association, has_one_association, patch, polymorphic, sti” to “2.3.2, activerecord, associations, association_preload, association_proxy, autosave_association, belongs_to_polymorphic_association, bugmash, has_many_association, has_many_through_association, has_one_association, patch, polymorphic, sti”
Santiago Pastorino February 2nd, 2011 @ 04:39 PM
- State changed from “new” to “open”
- Tag changed from “2.3.2, activerecord, associations, association_preload, association_proxy, autosave_association, belongs_to_polymorphic_association, bugmash, has_many_association, has_many_through_association, has_one_association, patch, polymorphic, sti” to “232, activerecord, associations, association_preload, association_proxy, autosave_association, belongs_to_polymorphic_association, bugmash, has_many_association, has_many_through_association, has_one_association, patch, polymorphic, sti”
- Importance changed from “” to “”
This issue has been automatically marked as stale because it has not been commented on for at least three months.

The resources of the Rails core team are limited, and so we are asking for your help. If you can still reproduce this error on the 3-0-stable branch or on master, please reply with all of the information you have about it and add "[state:open]" to your comment. This will reopen the ticket for review. Likewise, if you feel that this is a very important feature for Rails to include, please reply with your explanation so we can consider it.

Thank you for all your contributions, and we hope you will understand this step to focus our efforts where they are most helpful.
Santiago Pastorino February 2nd, 2011 @ 04:39 PM
- State changed from “open” to “stale”