Changing state is optional

For both sync and async reducers, returning a new state is optional. If you don't plan on changing the state, simply return null. This is the same as returning the state unchanged:

class GetAmountAction extends ReduxAction<AppState> {
  
  Future<AppState?> reduce() async {    
    int amount = await getAmount();
    
    if (amount == 0) 
      return null;
    else 
      return state.copy(counter: state.counter + amount));
  }
}

This is also useful if some action is used to simply start other async processes, or dispatch other actions. For example:

class InitAction extends ReduxAction<AppState> {
  
  AppState? reduce() {
    dispatch(ReadDatabaseAction());        
    dispatch(StartTimersAction());          
    dispatch(TurnOnListenersAction());
              
    return null;          
  }
}

Note the reduce() method has direct access to dispatch.

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Next, let's see how to reduce boilerplate by defining our own base action class.