Set offset and limit before query build

Currently, we can only use limit and offset as .find(long offset, long limit)

But, what If I want to listen to query changes but with limit and offset as results? Is that possible?
Example, I have 1000 messages, but I do show for a user only 100, if a user will scroll, then new messages will be loaded. Also, query automatically updates list if, a new message will be inserted into DB, but with same offset and limit.

Sounds reasonable, keeping this as a feature request.

I really need that feature too) Is it in work?

Looking for this, too. 👍

So if I understand correctly there is currently no way to limit the amount of objects an observable query returns, other than filtering it with properties?
Say I am only interested in the latest 5 objects, is there any way to get only the latest five objects via a query?

any update?

Is it feasible to use the ObjectBox-support for Jetpack Pagination for this?

Please see my comment on this other closed issue for more details on how to possibly do that.

I am also looking for a way to limit the number of results returned from an observer.

I didn't test this, but it should be possible to use Android Jetpack Paging with the ObjectBoxDataSource.Factory to get a LiveData-instance that supports limited items query, as described here:

https://docs.objectbox.io/android/paging-architecture-components

So, you could do something like this (but you would have to add the Android Jetpack Paging dependency for this to work):

public class NotePagedViewModel extends ViewModel {
    
    private LiveData<PagedList<Note>> noteLiveDataPaged;
    
    public LiveData<PagedList<Note>> getNoteLiveDataPaged(Box<Note> notesBox) {
        if (noteLiveDataPaged == null) {
            // query all notes, sorted a-z by their text
            Query<Note> query = notesBox.query().order(Note_.text).build();
            // build LiveData
            noteLiveDataPaged = new LivePagedListBuilder<>(
                    new ObjectBoxDataSource.Factory<>(query),
                    20 /* page size */
            ).build();
        }
        return noteLiveDataPaged;
    }
}

(copied from above-mentioned objectbox-docs-page)

Would that solve your problem?

If the above ObjectBoxDataSource is not an option, here is how to get started with your own general DataObserver that runs a query with limit and offset:

class LimitOffsetNoteObserver(
    private val store: BoxStore,
    private val observer: DataObserver<List<Note>>,
    private val offset: Long,
    private val limit: Long
) : DataObserver<Class<Note>> {
    override fun onData(data: Class<Note>) {
        val results = store.boxFor(Note::class)
            .query(Note_.text.contains("TODO"))
            .build()
            .find(offset, limit)
        observer.onData(results)
    }
}

// Keep the subscription while used 
// to avoid garbage collection of the observer.
subscription = store.subscribe(Note::class.java)
    .observer(LimitOffsetNoteObserver(store, observer, offset, limit))

Side note: this also affects the RxJava(3) wrapper classes: greenrobot/ObjectBoxRxJava#3

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Set offset and limit before query build #303

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Set offset and limit before query build #303

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greenrobot commented on Dec 7, 2017

sapelkinAV commented on Mar 18, 2018

Queatz commented on Sep 21, 2018

hendrep commented on Oct 5, 2018

TinoGuo commented on Oct 23, 2018

ajans commented on Feb 22, 2021

Queatz commented on Jul 5, 2021

ajans commented on Jul 8, 2021

greenrobot-team commented on Apr 4, 2022

greenrobot-team commented on Sep 21, 2026

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