Android app architecture

MusicBrainz Development
2

Two livedata for Artist detail and releases

As there are many queries to make to fill an artist info, I propose an architecture something like this:

MusicBrainz%20Android
MusicBrainz%20Android771×341 19.2 KB

  1. When Activity receives the MBID in the Intent, asks the ViewModel to start fetching the artist data.
  2. ViewModel then will get the artist from the repository. Once it has the artist with its releases:
    1. Updates the artist LiveData, which will be observed by the Details Fragment to show name/birth_data/etc.
    2. Transforms the stream by getting the releases and for each one queries the Repository to get the cover art URLs for each release. Then updates a different releases LiveData (that includes release info and cover URLs) that will be observed by Releases Fragment to render a list.

Other alternative:

Instead of querying all the releases for the URL, another alternative is returning releases like List<Pair<Release,Url>>. And do something like if viewholder asks the viewModel to update release X with its cover art –> viewModel re-emits the same release list (but that release item will have URL info) –> notifies the recyclerview -> viewholder now binds an item that has URL inside on it.