Deprecate Partial Objects

[beberlei]

We plan to remove partial objects in the forseeable future. This doesn't have to be ORM 3, because it depends on a few alternatives being in place.

Partial objects are a bad fix for wanting to avoid loading too much data like text fields /blobs that are not needed in the request. Three solutions are proposed to migrate towards around this deprecation and removal:

• Use data transfer objects with the SELECT new MyDTO()
• Use new fetch=Eager support with Query::setFetchMode to implement multi-step hydration: [GH-1569] Optimize eager fetch for collections to batch query #8391
• Add support for lazy loading some properties or embeddables through a better proxy manager (this is not supported yet) Use ProxyManager #8518

As for use of PARTIAL with array hydration, a potential solution could be the introduction of a dedicated function: PARTIAL(alias, ...) that does the same that PartialExpression previously did. This could encapsulate this logic in ArrayHydrator and a specific function and avoid the polution of the DQL language with this concept.

Update: Deprecation reverted in ORM 2.20.0 and 3.3.0-dev

See #8471 (comment)

[gharlan]

I sometimes use the trick from the section "Coding multi-step hydration in Doctrine ORM" from https://ocramius.github.io/blog/doctrine-orm-optimization-hydration/.

What is the best way to migrate from this?

[pszalko]

I have the same concerns as @gharlan. Is there any way to migrate? @beberlei

[stepozer]

I believe the best way for this will be just allow developers to specify what exactly you want to load as we have in ActiveRecord in Laravel - https://laravel.com/docs/8.x/eloquent-relationships#eager-loading. I believe this feature will be useful to avoid this terrible joins with OneToMany hydration. And doctrine should automatically decide is it leftJoin or SELECT FROM IN request.

@beberlei what do you think?

[AlexisFinn]

Hello, just to be clear, do you plan on removing partial arrays, as in

$qb->selec('partial  user.{id, name}')
->getQuery()->getArrayResult();

Because that's actually really usefull for retrieving a nicely formatted array.