objectbox / objectbox/objectbox-java

Request : LiveData observing Query.count instead of Query.find

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enhancement
Dominant language
Java
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Description

Hi,

I'd like to use LiveData to observe the number of items resulting of a given query (the equivalent of Query.count() or Query.findLazy().size()).

As of v2.4.0, LiveData only calls Query.find, so the only implementation I came up with is not optimal at all

// Get all results as objects
// NB : db.queryContentSearch is a Query<Content>
ObjectBoxLiveData<Content> livedata = new ObjectBoxLiveData<>(db.queryContentSearch(query, metadata, favouritesOnly));

// Instanciated objects are useless because we just actually count them !
MediatorLiveData<Integer> result = new MediatorLiveData<>();
result.addSource(livedata, v -> result.setValue(v.size()));
return result;

=> Would it be possible in future versions to build LiveData's that observe Query.count ?
Or have I overlooked a feature that already exists ?

Thanks a lot for your help,
-Robb

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reviewing the current LiveData behavior that calls Query.find, then compare the Query.count and Query.findLazy APIs described in the issue. Done means a LiveData option can observe a query's count without materializing all result objects and updates when the query results change.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, java
Domain
database, mobile
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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