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Feature Request: Android Paging Library support

See original GitHub issue

Is your feature request related to a problem? Please describe The Android Paging library is becoming the standard way to handle paging on Android. As far as I know, it currently does not work with Groupie yet. It would be great to add support for the library to Groupie.

@chibatching has written an article on how to connect the Paging library with Groupie. This is a great start, I’m not sure it’s the ideal solution:

It requires you to have a PagedList containing groupie Items. This is not a great separation of concern. We want the DataSource to provide data, not groupie Items to keep the DataSource free from any view related logic. The post suggests passing a transform function to the datasource, which works, but it still means that the ViewModel is exposing a PagedList of groupie items. You could transform the PagedList by using the .map function on the DataSourceFactory. However this means losing any additional information on the factory (such as a LiveData exposing error states).
It loads all content into a single Group. I’m not sure if this is a problem but ideally you’d submit the paged list directly into the adapter.
It’s not a native solution that the library provides

Describe the solution you’d like First-class support for the paging library in the main groupie library or perhaps an additional module.

Option 1

Add a update(p pagedList<T>, t TransformFunction) function to GroupAdapter.

This function takes a PagedList of any raw data, and a transform function that maps the data to groupie items.

Option 2

Add a update(p PagedList<T: Item>) function to GroupAdapter.

This still requires that the PagedList is mapped to groupie items by the consumer first.

Additional context If this is something you would consider adding to the library, I’d be happy to give it a shot and see if I can come up with a PR.