FirestoreDataSource - Please add the ability to get an occurred exception

[Zeliret]

Right now I can only get an error status and call retry. But I need to get the exact exception to provide an explanation to my users.
I have found the place where the error state is populated and It seems that I need to override a lot of code to get the error message.
Is there a good way to workaround this?

[samtstern]

@Zeliret can you show an example of the code you're using now and maybe some comments on how you'd want it to improve?

[Zeliret]

@samtstern sure. Thanks for the answer.
So, I have a Query instance and configured PagedList builder.
I create a new adapter:

val options = FirestorePagingOptions.Builder<Trip>()
                        .setLifecycleOwner(this)
                        .setQuery(result.data.query, Source.DEFAULT, pagingConfig) {
                            result.data.converter(it)
                        }
                        .build()

                    binding.tripsList.swapAdapter(TripsAdapter(options), false)

Let's assume I get an error while I'm loading a page. I can check it here:

override fun onLoadingStateChanged(state: LoadingState) {
            if( state == LoadingState.ERROR ) {
                retry()
            }
        }

But I can get only the flag. How can I get the actual error? As far as I can see from the source code:

/**
     * Error listener that logs, sets the error state, and sets up retry.
     */
    private abstract class OnLoadFailureListener implements OnFailureListener {

        @Override
        public void onFailure(@NonNull Exception e) {
            Log.w(TAG, "load:onFailure", e);

            // On error we do NOT post any value to the PagedList, we just tell
            // the developer that we are now in the error state.
            mLoadingState.postValue(LoadingState.ERROR);

            // Set the retry action
            mRetryRunnable = getRetryRunnable();
        }

        protected abstract Runnable getRetryRunnable();
    }

Here the exception just dumped into the log.
So I can not check if it is a network error or show it to the user.

[samtstern]

@Zeliret ah I see that's a good feature request! You're right, there's no good way to get it right now in the Paginated adapters.

[samtstern]

How would you feel about something like a getLastError() call in the paginated adapter classes?

[Zeliret]

How would you feel about something like a getLastError() call in the paginated adapter classes?

That sounds good.
So I could use the flow:

if( state == LoadingState.ERROR ) {
     val ex = getLastError()
     if( ex is IOException )
         retry()
     else
         showErrorMessage(ex)
}

As for me that should works. Thank you! :)

[samtstern]

Yep that's how I imagine it too.

[PatilShreyas]

We should solve this issue together as same as we implemented in FirebaseRecyclerPagingAdapter.
As we discussed here in PR #1603.

We will override the method as

protected void onError(Exception e) {
}

...and will implement as...

@Override
protected void onError(@NonNull Exception e) {
        mSwipeRefreshLayout.setRefreshing(false);
        Log.e(TAG, e.getMessage(), e);
 }

After this, users will able to get status about caught Exception.
Will it helpful?

[samtstern]

This has been fixed and released in 5.0.0