Android Paging 3 - get list of data from PagingData<T> object

user_11006132 0
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I'm using new jetpack Paging 3 library. I have one specific use case. I want to share this data between two screens using viewmodel.

One screen needs paged data and for the second screen I want simple list of this data (not paged list, I need to work with the list...). I do not want list in object of PagingData.

Is there any way how to get the list without PagingData object ? enter image description here

As you can see there is no variable the get this data. I tried it even in viewModel when flow is created but I haven't found solution.

android-recyclerview paging list android pagination
2 Answers

PagingData is just a stateless stream of incremental load events, so it does not hold this kind of state.

However PagingDataAdapter / Differ (and similarly other presenter-side variants), already need to hold the data, so they expose APIs such as PagingDataAdapter.snapshot() which can give you the current list of presented items.

Keep in mind that the presented data is post-transformation, may not include pages that were dropped due to exceeding maxSize, and also may race with fetcher as it takes some time between loading the data, and having it show up in UI.

It really depends on what you're interested in tracking exactly, but from the fetcher side (tracking pre-transform) you can either build the list from results returned in PagingSource or you can also write a no-op .map() operator on PagingData which will see every item (but not give you information about order).

Unfortunately Paging3 doesn't yet offer a non-ui collector that can build this state for you (most useful in testing), but this is hopefully something we can look into in the future.

user_14523820

To expand on dlam's comment, it is possible to retrieve the list of data of PagingData, as long as it is connected to a PagingDataAdapter, or if the PagingData result is submitted to a AsyncPagingDataDiffer.

To do that, invoke

adapter.snapshot().items

if connected to a PagingDataAdapter, or

differ.snapshot().items

if connected to a AsyncPagingDataDiffer.

user_55227200
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