Refs #28025 nullify *_type column on polymorphic associations on :nu…

[laertispappas]

Nullify polymorphic *_type column on dependent: :nullify strategy.

Summary

This PR addresses the issue described in #28025. On dependent: :nullify strategy only the foreign key of the relation is nullified. However on polymorphic associations the *_type column is not nullified leaving the record with a NULL *_id but the *_type column is present.

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[haines]

Nice! I think this needs to be extended to handle to polymorphic has_one relationships as well.

[gmcgibbon]

Still relevant in Rails 6 (205aa14). I agree with @haines, behaviour should be consistent with has_one if its going to be changed. I think all you need to do is add record[reflection.type] = nil if reflection.type to

rails/activerecord/lib/active_record/associations/has_one_association.rb

Line 97 in 205aa14

def nullify_owner_attributes(record)

and add another test.

[laertispappas]

@gmcgibbon @haines thanks for the feedback. I made some changes can you have a look?

[haines]

Thanks for adding it to the has_one, this looks good to me!

[gmcgibbon]

Nice job! Please squash your commits and add a changelog entry in activerecord/CHANGELOG to make this mergeable.

[laertispappas]

@gmcgibbon thank you for the feedback. Squashed and updated CHANGELOG / docs.

[gmcgibbon]

Sorry, two more things and then it should be good to go!

[laertispappas]

@gmcgibbon Updated. Thanks.

[eileencodes]

This looks good to me. Sorry for the delay @laertispappas - can you fix the conflicts and I can merge once that's done.

[laertispappas]

@eileencodes @kamipo thanks for the feedback. I've made some changes.

[kamipo]

Thanks!

[laertispappas]

Pleasure