Introduction

Debugging is an essential part of Flutter development. GetX provides several tools and patterns to make debugging easier, from simple logging to tracking reactive state changes. This guide covers how to effectively log events, debug controllers, monitor navigation, and use DevTools with GetX. You'll learn techniques to catch issues early and build more reliable apps.

Basic Logging with print and debugPrint

The simplest way to log is using print(). However, on large outputs, Flutter may truncate long strings. Use debugPrint() instead – it splits long strings into chunks, preventing truncation.

DARTRead-only

void main() {
  debugPrint('App started');
  runApp(MyApp());
}

class MyController extends GetxController {
  void doSomething() {
    debugPrint('Button clicked');
  }
}

void main() {
  debugPrint('App started');
  runApp(MyApp());
}

class MyController extends GetxController {
  void doSomething() {
    debugPrint('Button clicked');
  }
}

GetX's Built‑in Logging

GetX provides a static Get.log() method that formats logs with a timestamp and a prefix. It's useful for distinguishing logs from different parts of the app.

DARTRead-only

Get.log('Login attempt');
Get.log('API call succeeded', isError: false);
Get.log('Error occurred', isError: true);

Get.log('Login attempt');
Get.log('API call succeeded', isError: false);
Get.log('Error occurred', isError: true);

Logging Controller Lifecycle

Add logs in onInit, onReady, and onClose to verify that controllers are being created and disposed correctly.

DARTRead-only

class MyController extends GetxController {
  @override
  void onInit() {
    super.onInit();
    debugPrint('MyController initialized');
  }

  @override
  void onReady() {
    super.onReady();
    debugPrint('MyController ready');
  }

  @override
  void onClose() {
    debugPrint('MyController closed');
    super.onClose();
  }
}

class MyController extends GetxController {
  @override
  void onInit() {
    super.onInit();
    debugPrint('MyController initialized');
  }

  @override
  void onReady() {
    super.onReady();
    debugPrint('MyController ready');
  }

  @override
  void onClose() {
    debugPrint('MyController closed');
    super.onClose();
  }
}

Debugging Reactive State Changes

Use workers to log when reactive variables change. This is invaluable for understanding why your UI updates (or doesn't).

DARTRead-only

class CounterController extends GetxController {
  var count = 0.obs;

  @override
  void onInit() {
    super.onInit();
    ever(count, (value) {
      debugPrint('Count changed to $value');
    });
  }
}

class CounterController extends GetxController {
  var count = 0.obs;

  @override
  void onInit() {
    super.onInit();
    ever(count, (value) {
      debugPrint('Count changed to $value');
    });
  }
}

Debugging Navigation

To log every navigation, you can use Get.routeObserver or add a global middleware. A middleware can log route changes.

DARTRead-only

class LoggingMiddleware extends GetMiddleware {
  @override
  List<GetPage> onPageCalled(GetPage page) {
    debugPrint('Navigating to ${page.name}');
    return [page];
  }
}

// Add to GetPage
GetPage(
  name: '/home',
  page: () => HomePage(),
  middlewares: [LoggingMiddleware()],
);

class LoggingMiddleware extends GetMiddleware {
  @override
  List<GetPage> onPageCalled(GetPage page) {
    debugPrint('Navigating to ${page.name}');
    return [page];
  }
}

// Add to GetPage
GetPage(
  name: '/home',
  page: () => HomePage(),
  middlewares: [LoggingMiddleware()],
);

Alternatively, set a global routing callback in GetMaterialApp:

DARTRead-only

GetMaterialApp(
  routingCallback: (routing) {
    debugPrint('Route: ${routing?.current}');
  },
);

GetMaterialApp(
  routingCallback: (routing) {
    debugPrint('Route: ${routing?.current}');
  },
);

Logging API Calls with Interceptors

If you use Dio, add a logging interceptor to log requests and responses. This is extremely helpful for debugging network issues.

DARTRead-only

dio.interceptors.add(LogInterceptor(
  requestBody: true,
  responseBody: true,
));

dio.interceptors.add(LogInterceptor(
  requestBody: true,
  responseBody: true,
));

Using Flutter DevTools with GetX

Flutter DevTools provides a rich debugging experience. To inspect reactive state, you can use the 'Widget Inspector' to see widget rebuilds, and the 'Memory' tab to verify controllers are being disposed. Add breakpoints in onInit and onClose to trace lifecycle.

Debugging Workers

If a worker isn't triggering, check that the reactive variable is actually changing. Add logs inside the worker callback and ensure the variable is updated. Also verify that the worker is registered after the variable is created (in onInit).

DARTRead-only

debounce(query, (value) {
  debugPrint('Debounce triggered for: $value');
}, time: Duration(milliseconds: 500));

debounce(query, (value) {
  debugPrint('Debounce triggered for: $value');
}, time: Duration(milliseconds: 500));

Logging Errors Globally

Use the global error handling techniques covered in the getx-global-error-handler topic to log all uncaught exceptions. This helps catch issues that might otherwise go unnoticed.

DARTRead-only

FlutterError.onError = (details) {
  debugPrint('Flutter error: ${details.exception}');
};
PlatformDispatcher.instance.onError = (error, stack) {
  debugPrint('Uncaught error: $error');
  return true;
};

FlutterError.onError = (details) {
  debugPrint('Flutter error: ${details.exception}');
};
PlatformDispatcher.instance.onError = (error, stack) {
  debugPrint('Uncaught error: $error');
  return true;
};

Performance Logging

To measure performance, use Stopwatch around critical operations. Log the duration to spot bottlenecks.

DARTRead-only

final stopwatch = Stopwatch()..start();
await heavyOperation();
stopwatch.stop();
debugPrint('Heavy operation took ${stopwatch.elapsedMilliseconds} ms');

final stopwatch = Stopwatch()..start();
await heavyOperation();
stopwatch.stop();
debugPrint('Heavy operation took ${stopwatch.elapsedMilliseconds} ms');

Best Practices

Use debugPrint instead of print – Prevents truncation.
Log controller lifecycle – Helps ensure proper disposal.
Use workers to track state changes – Great for debugging reactive flow.
Add middleware for route logging – Track navigation easily.
Use a logging interceptor for HTTP – See exactly what is sent/received.
Keep logs informative but not noisy – Avoid flooding the console in production.
Use conditional logging – Wrap logs with kDebugMode to avoid logging in release builds.
Use DevTools – Leverage inspector and memory tools.

Common Mistakes

❌ Using print for long strings – May get truncated. ✅ Use debugPrint.
❌ Logging sensitive data – Tokens, passwords, etc. ✅ Redact or avoid logging sensitive info.
❌ Forgetting to add logs in workers – Hard to know if they fire. ✅ Add logs to see when workers run.
❌ Logging too much in production – Can impact performance and expose data. ✅ Use kDebugMode or a configuration flag.

FAQ

Q: How do I log only in debug mode?
A: Use if (kDebugMode) debugPrint(...). kDebugMode is a constant from foundation.dart that is true in debug builds.
Q: Can I use Get.log with custom tags?
A: Get.log doesn't support custom tags out of the box, but you can create your own wrapper.
Q: How to see which widgets are rebuilding?
A: Use DevTools' 'Widget Inspector' with 'Highlight repaints' enabled. This shows green borders around widgets that rebuild.
Q: Why is my worker not triggering?
A: Ensure the reactive variable is being updated (check with a log). Also ensure the worker is set up in onInit, not after the variable changes.
Q: How to log the entire state of a controller?
A: Override toString in your controller and call it from a debug function, or use debugPrint(controller.toString()).

Conclusion

Effective logging and debugging are essential for building reliable Flutter apps. GetX provides the building blocks to log state changes, lifecycle events, and navigation. By combining these with Flutter's DevTools and best practices, you can quickly identify and fix issues during development.

Test Your Knowledge

of 3

Which function should you use to print long strings without truncation?

print()

debugPrint()

console.log()

log()

of 3

How can you log every time a reactive variable changes?

Use a worker like ever

Use Get.log inside the setter

Override the variable's setter

Use debugPrint in the UI

of 3

Which GetX feature can you use to log route changes globally?

Get.logRoute

routingCallback

Get.routeObserver

Both B and C

class MyController extends GetxController { @override void onInit() { super.onInit(); debugPrint('MyController initialized'); } @override void onReady() { super.onReady(); debugPrint('MyController ready'); } @override void onClose() { debugPrint('MyController closed'); super.onClose(); } }

class CounterController extends GetxController { var count = 0.obs; @override void onInit() { super.onInit(); ever(count, (value) { debugPrint('Count changed to $value'); }); } }

class LoggingMiddleware extends GetMiddleware { @override List<GetPage> onPageCalled(GetPage page) { debugPrint('Navigating to ${page.name}'); return [page]; } } // Add to GetPage GetPage( name: '/home', page: () => HomePage(), middlewares: [LoggingMiddleware()], );

FlutterError.onError = (details) { debugPrint('Flutter error: ${details.exception}'); }; PlatformDispatcher.instance.onError = (error, stack) { debugPrint('Uncaught error: $error'); return true; };

Test Your Knowledge

of 3

Which function should you use to print long strings without truncation?

print()

debugPrint()

console.log()

log()

of 3

How can you log every time a reactive variable changes?

Use a worker like ever

Use Get.log inside the setter

Override the variable's setter

Use debugPrint in the UI

of 3

Which GetX feature can you use to log route changes globally?

Get.logRoute

routingCallback

Get.routeObserver

Both B and C

GetX Logging & Debugging: Track State, Errors & Performance

GetX Logging & Debugging: Track State, Errors & Performance

Introduction

Basic Logging with print and debugPrint

GetX's Built‑in Logging

Logging Controller Lifecycle

Debugging Reactive State Changes

Debugging Navigation

Logging API Calls with Interceptors

Using Flutter DevTools with GetX

Debugging Workers

Logging Errors Globally

Performance Logging

Best Practices

Common Mistakes

FAQ

Conclusion

Test Your Knowledge

Need help?

GetX Logging & Debugging: Track State, Errors & Performance

GetX Logging & Debugging: Track State, Errors & Performance

Introduction

Basic Logging with print and debugPrint

GetX's Built‑in Logging

Logging Controller Lifecycle

Debugging Reactive State Changes

Debugging Navigation

Logging API Calls with Interceptors

Using Flutter DevTools with GetX

Debugging Workers

Logging Errors Globally

Performance Logging

Best Practices

Common Mistakes

FAQ

Conclusion

Test Your Knowledge

Need help?