Action mixins

You can add mixins to your actions, to accomplish common tasks.

Check for Internet connectivity

CheckInternet ensures actions only run with internet, otherwise an error dialog prompts users to check their connection:

class LoadText extends Action with CheckInternet {
      
   Future<String> reduce() async {
      var response = await http.get('https://dummyjson.com/todos/1');
      ...      
   }
}   

NoDialog can be added to CheckInternet so that no dialog is opened. Instead, you can display some information in your widgets:

class LoadText extends Action with CheckInternet, NoDialog { 
  ... 
  }

class MyWidget extends StatelessWidget {
  Widget build(context) {     
     if (context.isFailed(LoadText)) Text('No Internet connection');
  }
}   

AbortWhenNoInternet aborts the action silently (without showing any dialogs) if there is no internet connection.

NonReentrant

To prevent an action from being dispatched while it's already running, add the NonReentrant mixin to your action class.

class LoadText extends Action with NonReentrant {
   ...
   }

Retry

Add Retry to retry the action a few times with exponential backoff, if it fails. Add UnlimitedRetries to retry indefinitely:

class LoadText extends Action with Retry, UnlimitedRetries {
   ...
   }

Debounce (soon)

To limit how often an action occurs in response to rapid inputs, you can add the Debounce mixin to your action class. For example, when a user types in a search bar, debouncing ensures that not every keystroke triggers a server request. Instead, it waits until the user pauses typing before acting.

class SearchText extends Action with Debounce {
  final String searchTerm;
  SearchText(this.searchTerm);
  
  final int debounce = 350; // Milliseconds

  Future<AppState> reduce() async {
      
    var response = await http.get(
      Uri.parse('https://example.com/?q=' + encoded(searchTerm))
    );
        
    return state.copy(searchResult: response.body);
  }
}

Throttle (soon)

To prevent an action from running too frequently, you can add the Throttle mixin to your action class. This means that once the action runs it's considered fresh, and it won't run again for a set period of time, even if you try to dispatch it. After this period ends, the action is considered stale and is ready to run again.

class LoadPrices extends Action with Throttle {  
  
  final int throttle = 5000; // Milliseconds

  Future<AppState> reduce() async {      
    var result = await loadJson('https://example.com/prices');              
    return state.copy(prices: result);
  }
}

OptimisticUpdate (soon)

To provide instant feedback on actions that save information to the server, this feature immediately applies state changes as if they were already successful, before confirming with the server. If the server update fails, the change is rolled back and, optionally, a notification can inform the user of the issue.

class SaveName extends Action with OptimisticUpdate { 
   
  async reduce() { ... } 
}