Problem Statement
What are optimistic updates in RTK Query and how do you implement them?
Explanation
Optimistic updates allow you to immediately update the UI before the mutation completes on the server, providing instant feedback to users and making the application feel faster by assuming the request will succeed. You implement this using the onQueryStarted lifecycle in mutation endpoints where you manually update the cache using patchResult to optimistically modify relevant query data, then handle the await queryFulfilled to either keep the optimistic update on success or revert it on error using the undo method. This pattern requires carefully considering rollback scenarios, showing appropriate error messages when optimistic updates fail, and ensuring your cache updates match the expected server response structure.
