I was using live data with paging library 2 but no...

# android

[Striker]

I was using live data with paging library 2 but now i upgraded to paging 3..I have a listData(which is a flow that returns paging data) and a searchQuery(livedata) and filterBy(livedata) so whenever i change it i also need the pagingdata to be updated...should i use MediatorLiveData ? Or is there any method using slow for this ?

[okarm]

Transformations.switchMap will be your friend here.
https://developer.android.com/reference/androidx/lifecycle/Transformations

[okarm]

I'll give you a hint from my codebase

private val selection = MutableLiveData<DateSelection>(Today)

val pagedReceipts: LiveData<PagingData<ReceiptPostBody>> = selection.switchMap { dateSelection ->
    Pager(config = ...,
        initialKey = ...,
        pagingSourceFactory = { MyPagingSource() }
    ).liveData
}

[Striker]

if it was one then this works...but as i said i have two live data filterBy and searchQuery and whenever any of these change i need to update the list

[Striker]

sorry misspelled flow as slow😅

[okarm]

@Striker Yes, MediatorLiveData is used for this.

https://github.com/Zhuinden/livedata-combinetuple-kt/blob/master/livedata-combinetuple-kt/src/main/java/com/zhuinden/livedatacombinetuplekt/LiveDataCombineTuple.kt#L22

[Striker]

isn't using flow better than using livedata ? and can we use channel or something for the two livedata(filter,query) ? And whenever this change return the pager as flow ? i couldn't find any similar example for this...

[okarm]

@Striker If you really need or want to use Flow instead of LiveData you can use the LiveData.asFlow() extension function to convert your filterBy and searchQuery into `Flow`s and then use combine and flatMapConcat to produce the final Flow<PagingData>

It would look something like this:

val latestPagingData: Flow<PagingData<SomeModel>> = searchQuery.asFlow().combine(filterBy.asFlow()) { query, filter -> Pair(query, filter) }.flatMapConcat { params -> Pager(...).flow }

[Striker]

Thanks...is there any problem with this method ? and could you give any reference to these operators(documentation,samples etc...)as i dont understand flatMapConcat etc...