Logging and error reporting

Riverpod natively offers a way to listen to all events happening in the provider tree.
This can be used to log all the events, or to report errors to a remote service.

This is achieved by using the ProviderObserver class, and passing it to ProviderScope/ProviderContainer.

Defining a ProviderObserver

A ProviderObserver is a class that should be extended.
It offers various methods which can be overridden to listen to events:

• didAddProvider, called when a provider is added to the tree
• didUpdateProvider, called when a provider is updated
• didDisposeProvider, called when a provider is disposed
• providerDidFail, when a synchronous provider throws an error

class MyObserver extends ProviderObserver {
  @override
  void didAddProvider(
    ProviderBase<Object?> provider,
    Object? value,
    ProviderContainer container,
  ) {
    print('Provider $provider was initialized with $value');
  }

  @override
  void didDisposeProvider(
    ProviderBase<Object?> provider,
    ProviderContainer container,
  ) {
    print('Provider $provider was disposed');
  }

  @override
  void didUpdateProvider(
    ProviderBase<Object?> provider,
    Object? previousValue,
    Object? newValue,
    ProviderContainer container,
  ) {
    print('Provider $provider updated from $previousValue to $newValue');
  }

  @override
  void providerDidFail(
    ProviderBase<Object?> provider,
    Object error,
    StackTrace stackTrace,
    ProviderContainer container,
  ) {
    print('Provider $provider threw $error at $stackTrace');
  }
}

Using a ProviderObserver

Now that we've defined an observer, we need to use it.
To do so, we should pass it to either ProviderScope or ProviderContainer:

runApp(
  ProviderScope(
    observers: [
      MyObserver(),
    ],
    child: MyApp(),
  )
);

final container = ProviderContainer(
  observers: [
    MyObserver(),
  ],
);