Add setting to EntityReferenceSelection plugins to prevent references to referencing entity

This would be really really useful. It's very common to have Content referencing other content of the same type to create blocks like "Related Articles", "Recommended products" and editors being responsible to curate these blocks by choosing the specific nodes in the entity reference field.

I tested the patch from #79 and it did not work as I show in the video attached:
Screenshare - 2023-02-07 12_05_04 PM.mp4 (3.96 MB)

For, d10 #79 patch not applied cleanly.
Fix for d10

This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request → as a guide.

Issue summary should include the proposed solution to the problem.

Also since we are adding a new setting this seems like it could affect existing sites. Think we would need an upgrade path.

This needs to be redone on top of 🐛 Entity autocomplete widget does not pass along entity to AJAX request Fixed . That issue already added a test implementation for this, we just need to convert that to a setting like this issue is doing. We can probably remove the test implementation there again.

Liam Morland → made their first commit to this issue’s fork.

I have created a merge request with the patch in #88 ported to 11.x.

Upgrade path: Perhaps the variable should be prevent_self_reference instead of allow_self_reference. That way, if it is not set, it has the same behaviour as before. Nothing changes until someone configures it differently.

The upgrade path already works. I installed this on my 10.2.4 site. In my test field, allow_self_reference was already checked and self-reference was allowed, as before. I unchecked it and self-reference was prevented.

Patch from merge request ported to Drupal 10.2.4.

The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

The bot is referring to the patch in 97. The current version is the merge request.

The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

Consult the Drupal Contributor Guide → to find step-by-step guides for working with issues.

Patch from merge request, just to stop the bot from resetting the status.

If going to add a new UI setting will probably need usability sign off.

Also with schema change going to an upgrade path.

Who does the usability sign-off?

Does this need an upgrade hook or would it be OK to write it so that if allow_self_reference is not set, is is treated as true to preserve existing behaviour?

Can post in #ux for them to take a look, they also keep an eye on the tag.

If a configuration file is being updated it will need an upgrade path.

I rebased the merge request on 11.x. The patch is the current state of the merge request.

Test are now passing.