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android / architecture-components-samples

Samples for Android Architecture Components.
https://d.android.com/arch
Apache License 2.0
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[Paging]Is there a way to display the offline data firstly while pulling the fresh data from remote? #864

Closed TonnyL closed 4 years ago

TonnyL commented 4 years ago

I'm doing the migration work to paging3 and I get this problem: every time I open my app, it displays a refreshing state(like the PagingWithNetwork(db+network) app does) with an empty list screen, but I want to display the offline data (maybe outdated) firstly while it is refreshing like many other apps does(google podcasts, for example).

For paging2, my solution is MediatorLiveData, db data first, then network data, it seems doesn't work anymore for paging3. It there a way to achieve this for paging3?

dlam commented 4 years ago

Thanks for reporting this, right now remote REFRESH is resolved synchronously and per your use-case I'm not sure this is desired behavior.

As a workaround, you can launch within RemoteMediator.load() for the REFRESH case and immediately return MediatorResult.Success(false). If the remote REFRESH job has new items, the correct behavior is to still write to DB and invalidate PagingSource (unless nothing has changed). If you are using Room for local caching such as in the sample, any row updates will automatically invalidate PagingSource implementations generated by Room.

In the future, the best place to file issues with the library is through our issuetracker: https://issuetracker.google.com/issues/new?component=413106&template=1096385

dlam commented 4 years ago

In the meantime I've filed here to track: http://issuetracker.google.com/issues/160062540

TonnyL commented 4 years ago

Thx, I'll keep an eye on it.

TonnyL commented 4 years ago

Many thanks to you, it works for me with the paging snapshot build.