Single source of truth
Single source of truth
What is Single source of truth principle?
For every data type defined in your app (i.e a Note or User type) you should assign a Single Source of Truth (SSOT) to it. So this SSOT is the owner of that data and only he can expose the data using a inmutable type, and to modify data the SSOT exposes methods that are accessible from other layers. (This should be the Repository calling an API or Dao for a data base).
In an offline-first application, the source of truth for application data is typically a database.
This pattern brings multiple benefits:
- It centralises all the changes to a particular type of data in one place.
- It protects the data so that other types cannot interfere with it.
- It makes changes to the data more traceable. Thus, bugs are easier to spot.