Internet mixins

The mixins explained in this page help us check for internet connectivity before running an action.

Mixin	Purpose	Overrides
CheckInternet	Checks internet before action; shows dialog if no connection	before
NoDialog	Modifier for CheckInternet to suppress dialog	(requires CheckInternet)
AbortWhenNoInternet	Checks internet before action; aborts silently if no connection	before
UnlimitedRetryCheckInternet	Combines internet check + unlimited retry + non-reentrant	abortDispatch, wrapReduce

---

CheckInternet

The CheckInternet mixin checks for internet connectivity before running the action. If there is no internet, the action aborts and a dialog opens with the message "There is no Internet. Please, verify your connection."

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

You can display information in your widgets when the action fails due to no connection:

if (context.isFailed(LoadText)) Text('No Internet connection');

Or use the exception text:

var errorText = context.exceptionFor(LoadText)?.errorText ?? 'No Internet';
if (context.isFailed(LoadText)) Text(errorText);

Customizing the error

To customize the dialog message or errorText, override connectionException() and return a custom UserException:

class LoadText extends AppAction with CheckInternet {

  UserException connectionException(List<ConnectivityResult> result) {
    return UserException('Custom error message');
  }
  ...
}

NoDialog

The NoDialog mixin can only be used together with CheckInternet. It prevents the error dialog from opening, while still aborting the action. This is useful when you just want to handle connectivity errors in your widgets instead of showing a dialog:

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

// Then, in your widget:
Widget build(context) {
  if (context.isFailed(LoadText)) {
    var message = context.exceptionFor(LoadText)?.errorText ?? 'No connection';
    return Text(message);
  }
  ...
}

Note: CheckInternet and NoDialog only check if the device's internet is on or off. They do not verify if the internet provider is working or if the server is available. The check may pass, but network requests can still fail.

UnlimitedRetryCheckInternet

The UnlimitedRetryCheckInternet mixin retries the action indefinitely until it succeeds. It checks for internet connectivity before each attempt and waits if there is no connection. It also retries if there is internet but the action fails for other reasons.

This is useful for critical actions that must eventually succeed, such as loading essential data when your app opens.

class LoadInitialData extends AppAction with UnlimitedRetryCheckInternet {
  Future<AppState?> reduce() async {
    var response = await http.get('http://myapp.com/initialData');
    return state.copy(data: response.body);
  }
}

This mixin automatically makes the action non-reentrant, so dispatching the same action while it's running will be ignored.

Parameters

You can override these parameters to customize retry behavior:

Parameter	Default	Description
initialDelay	350 ms	Delay before the first retry
multiplier	2	Factor by which delay increases each retry
maxDelay	5 sec	Maximum delay when retrying after errors (with internet)
maxDelayNoInternet	1 sec	Maximum delay when waiting for internet

The shorter maxDelayNoInternet allows faster recovery when connectivity returns.

Tracking retry attempts

Use the attempts getter to check the current retry count:

class LoadInitialData extends AppAction with UnlimitedRetryCheckInternet {
  Future<AppState?> reduce() async {
    print('Attempt number: $attempts');
    ...
  }
}

Logging retries

All retries are printed to the console by default. To disable or customize logging, override printRetries():

class LoadInitialData extends AppAction with UnlimitedRetryCheckInternet {
  void printRetries(String message) {} // Disable logging
  ...
}

Note: If your before method throws an error, retries will not happen.

Note: This mixin only checks if the device's internet is on or off. It does not verify if the internet provider is working or if the server is available. The check may pass, but network requests can still fail.

AbortWhenNoInternet

The AbortWhenNoInternet mixin checks for internet connectivity before running the action. If there is no internet, the action aborts silently, as if it had never been dispatched. No errors are thrown and no dialogs are shown.

class LoadText extends AppAction with AbortWhenNoInternet {
  Future<String> reduce() async {
    var response = await http.get('http://numbersapi.com/42');
    return response.body;
  }
}

Note: This mixin only checks if the device's internet is on or off. It does not verify if the internet provider is working or if the server is available. The check may pass, but network requests can still fail.

Simulating connectivity in tests

During tests, you can simulate the internet being on or off.

Option 1: Override internetOnOffSimulation in the action:

class LoadText extends AppAction with CheckInternet {
  bool? get internetOnOffSimulation => false; // Simulates NO internet
  ...
}

Return true to simulate having internet, false to simulate no internet, or null to use the real connectivity status.

Option 2: Set forceInternetOnOffSimulation on the store to affect all actions:

store.forceInternetOnOffSimulation = () => false; // Simulates NO internet for all actions

This applies to all actions using CheckInternet, AbortWhenNoInternet, or UnlimitedRetryCheckInternet. Since it's tied to the store, it resets automatically when the store is recreated.