Replace elements of ToMany collection without fetching them

[belovaf]

I have the following model:

@UpdatableEntityView
@EntityView(Parent::class)
interface ParentView {
    @get:IdMapping
    val id: Long?

    @get:MappingInverse(removeStrategy = REMOVE)
    @get:UpdatableMapping(orphanRemoval = true, cascade = [PERSIST])
    val children: MutableList<ChildView>
}

@CreatableEntityView
@EntityView(Child::class)
interface ChildView {
    @get:IdMapping
    val id: Long?
    var name: String
}

Is it possible to fetch ParentView and replace all its children without fetching them?
I have tried it with convert, but it doesn't work with collection attributes, because they are null after conversion.

[beikov]

Hi, what have you tried so far? You should be able to use something along the lines of this:

ParentView v = evm.getReference(ParentView.class, parentId);
v.setChildren( newChildren );
evm.saveFull(entityManager, v);

[beikov]

The main reason is to avoid overfetch. In practice I have 10-15 replace-only fields (including embedded json).

Can you share an example? I'm having a hard time imagining a UI that allows to replace a value only, without also showing the value.

Yes, you are right, with collections I'm getting those errors.

Got it, then please create a GitHub issue for that and I'll try to look into it :)

[belovaf]

Yes, I have a user profile settings usecase, for example.

1. User fetches all settings with view projection. Obviously I need to fetch all data here.
2. User PUTs updated version of settings. I don't care about previous values here, I just want to do update with optimistic locking. I intentionally don't use dirty checking here, because partial updates can lead to very huge amount of prepared statements.

Does it make sense?

[beikov]

Ok, that does make sense, though I believe in that particular case it would be more appropriate to use the getReference() approach. We just need to make sure that setting the version is possible. Applying the optimistic version is worth another GitHub issue :)

[belovaf]

Yes, you are right. I use find + convert as a workaround for getReference + set version.

Thank you, I will create two separate issues.

[belovaf]

I have created 2 issues: 1828, 1829.