[10.x] Added eachById and chunkByIdDesc to BelongsToMany

[lonnylot]

If you have a BelongsToMany pivot with a incrementing key then you can get the wrong id hydrated in the model and further operations would be on the wrong model.

Similar to #47479, but I think the incrementing key needs to be emphasized. People could be selecting in the current release and getting the wrong ID.

People are adding methods to BuildsQuery and not following through with maintaining BelongsToMany or HasManyThrough. Example: chunkByIdDesc was added a few months ago and nobody even thought about BelongsToMany #48666.

I'd ask internals to consider a larger rewrite as this doesn't appear to be well managed. I could keep writing failing tests (e.g. lazyByIdDesc or orderedLazyById), but I don't have time tonight. Additionally I'm guessing HasManyThrough (or anything else with a pivot) will have similar issues.

[lonnylot]

I'd ask internals to consider a larger rewrite as this doesn't appear to be well maintained.

I want to emphasize this even more and share that this bug has caused real world harm to my organization.

Someone in my organization, either confused by debugging Eloquent (beautiful software 🙇 , not the easiest to debug 🤗 ) or thinking primary keys on pivots weren't supported, wrote this code :

$relationship = $model->relationship();

$relationship->eachById(
      callback: fn ($relatedModel) => $relatedModel->delete(),
      column: $relationship->getQualifiedRelatedKeyName(),
      alias: 'id',
);

Because $relatedModel has the wrong primary ID we've been deleting the wrong rows and only just noticed now.

I cannot explain why this was done because it was done prior to me starting by someone no longer at the organization.

[taylorotwell]

Thanks 👍 I've fixed chunkByIdDesc on HasManyThrough as well, and lazyByIdDesc on both BelongsToMany and HasManyThrough

[lonnylot]

@taylorotwell Thank you 🙏