Pola Repository

Your ViewModel should not know about DAOs or networks. A repository hides those details behind a clean, simple interface.

The repository is the one place the rest of the app asks for data, whether it comes from Room, the network, or memory.

Give the repository the DAO and let it expose friendly methods. Callers see notes, not SQL queries.

Add purposeful functions like addNote. The name says what happens; the storage mechanism stays hidden inside.

Because callers depend on the repository, you can switch from Room to a fake or a remote API without touching the ViewModel.

Tests can pass a fake repository to the ViewModel, so you verify logic without a real database on disk. ✅

The ViewModel receives the repository through its constructor, never creating it directly. That keeps dependencies explicit.

A repository can merge cache and network, deciding what to return. The UI just asks once and stays unaware of the plumbing.

For reactive data the repository can simply forward the DAO Flow, adding transformations only when the app actually needs them.

Keep repositories focused: one for notes, one for users. Each owns a single area of data and its sources.

UI shows data, ViewModel holds state, repository fetches it, Room stores it. Each layer has one job and stays replaceable.

What is the main job of a repository in this architecture?

You put a repository between the ViewModel and your data, exposing actions and Flows while hiding the source. Next you will make it work offline first.