ToMany is automatically sorted by Entity id

[zoltish]

Issue Basics

• ObjectBox version (are using the latest version?): 1.4.4
• Reproducibility: Always

Reproducing the bug

Description

I have an Entity ExerciseEntity that contains a ToMany of BodypartEntity.

When creating a new ExerciseEntity, bodyparts are specified as A,B,C. Their ordering is important.

After inserting the entity into the Box, later on it will contain the bodyparts with a completely different order (e.g. B,A,C). From what I can tell theyre always sorted by their id annotated value.

Code

ExerciseEntity has lateinit var bodyparts: ToMany<BodypartEntity>
When creating a new one its assigned as entity.bodyparts.addAll(bodyparts)

[greenrobot-team]

That items are ordered by ID when loaded from the store is by design, see the docs on the method ToMany.sortById(). -ut

[zoltish]

@greenrobot-team I see! In that case -> How can I keep my own insertion order?

And out of curiosity, is it common to sort lists like this in storage solutions? I dont think Ive ever come across it prior to this, in my experience the natural order is the one theyre placed in when storing them?

[greenrobot-team]

I suppose the best solution is to instead query for the BodypartEntitys and then specify the sort order you want (for example you may add an order property to BodypartEntity). Example:

bodypartBox.query().equal(BodypartEntity_.exerciseId, exerciseId)
    .order(BodypartEntity_.order)
    .build().find()

Or: If you add an order property you obviously can sort the items of the ToMany yourself before getting them.
-ut

[greenrobot]

PS.: There's also an experimental setComparator(c) method in ToMany class, which you could set before the list is loaded.

[zoltish]

Thanks for the answers! 👍 I think Ill end up including the list index inside the object wherever it makes sense as you mention!

[greenrobot-team]

Closing this then.

Edit: this is also a duplicate of #243 and #154.
-ut