Add accepts_nested_attributes_for support for delegated_type

[xtr3me]

Summary

This PR adds nested_attributes_for support to delegated_type, this allows a developer to create and update records easily without needing to write specific methods like:

class Entry < ApplicationRecord
  delegated_type :entryable, types: %w[ Message Comment ]

  def self.create_with_comment(content, creator: Current.user)
    create! entryable: Comment.new(content: content), creator: creator
  end
end

Using nested_attributes_for allows to execute the following:

class Entry < ApplicationRecord
  delegated_type :entryable, types: %w[ Message Comment ]
  accepts_nested_attributes_for :entryable
end

params = { entry: { entryable_type: 'Comment', entryable_attributes: { content: 'Smiling' } } }
entry = Entry.create(params[:entry])

Why

Nested forms based on accepts_nested_attributes_for are very powerful and this is the last piece missing to also be able to use it on Delegated Types.

Question

Since this is a polymorphic belongs_to relationship, what other tests would we like to have? As it is already tested in TestNestedAttributesOnABelongsToAssociation

[rails-bot]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
Thank you for your contributions.

[zzak]

@xtr3me Could you rebase too please? I think this PR could use some more tests, but I also wouldn't put more work into this without getting approval on the base of the feature from another committer 🙏

[rails-bot]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
Thank you for your contributions.

[xtr3me]

Hi @zzak i have incorporated your suggestions and rebased with main, thank you for reviewing it 👍
I was wondering if you or anyone else for that matter could guide me in which tests are required extra?

[zzak]

@xtr3me Sorry for the late reply, could you squash your commits too please?

[xtr3me]

@zzak i've squashed the commits. Thank you very much for reviewing it.

[xtr3me]

@zzak I have rebased the branch with main. Is there anything else I could do to advance this into merging it in main?

[zzak]

Thanks for your patience @xtr3me I've pretty limited capacity right now, so hopefully another review can take a look 🙏

[xtr3me]

@dhh as the original composer of the delegated_types feature could you maybe help out by reviewing this PR and guide me on which changes are needed to get this merged in?

Or do you know somebody who can/has some spare time to review this PR? 👍

[dhh]

This is lovely. Thanks for working on it!

[ps-ruby]

Loved it 😍

[Piioo]

How to change from Message to Comment? (with removing the Message from DB)