Embedded Subset Pattern implementation

[etshy]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

I learned about this pattern when searching about when/what to embed etc. and I think it could be a great addition to doctrine-odm.
I'm not sure how it could be implemented yet but having an Attribute #[SubSet(number:5, sort: DESC)] in addition to an attribute #[ReferenceMany] to store the 5 most recents referenced directly on an embed could reduce read operation on the db.

I learned about this pattern on the mongodb website here and here

[malarzm]

I believe this resembles #2252 and also suffers the same challenge: tracking changes. ODM would need to know that a (let's say) review has been changed and update its product accordingly.

Also, while less sexy than an attribute, the pattern is already doable and quite elegant:

class Product
{
    #[ReferenceMany(targetClass: Review::class)]
    private Collection $reviews;

    #[EmbedMany(targetClass: PartialReview::class)]
    private Collection $recentReviews;

    public function addReview(Review $review)
    {
        $this->reviews[] = $review;
        $this->recentReviews[] = new PartialReview($review);
        // maybe pop one last recent reviews if there's too many
    }
}

You could even hide capping recent reviews with a custom collection :)

[etshy]

Yeah tracking changes and knowing when to fetch the whole references list is what made me think about the most and couldn't think any good solutions for that.