riverpod-observers

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Original

English

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Translation

Chinese

Riverpod — ProviderObservers

Riverpod — ProviderObserver

Instructions

说明

A ProviderObserver receives lifecycle events for providers (e.g. when a provider's value changes). Use it for logging, analytics, or debugging.

ProviderObserver 会接收provider的生命周期事件（例如provider的值发生变化时）。可将其用于日志记录、数据分析或调试。

Implementing an observer

实现观察者

Extend ProviderObserver and override the methods you need (e.g. didUpdateProvider). Pass instances to ProviderScope or ProviderContainer via the

observers

parameter.

继承ProviderObserver并按需重写方法（例如didUpdateProvider）。通过

observers

参数将实例传递给ProviderScope或ProviderContainer。

Example: logger

示例：日志记录器

dart

final class Logger extends ProviderObserver {
  @override
  void didUpdateProvider(
    ProviderObserverContext context,
    Object? previousValue,
    Object? newValue,
  ) {
    print('{"provider": "${context.provider}", "newValue": "$newValue"}');
  }
}

void main() {
  runApp(
    ProviderScope(
      observers: [Logger()],
      child: const MyApp(),
    ),
  );
}

dart

final class Logger extends ProviderObserver {
  @override
  void didUpdateProvider(
    ProviderObserverContext context,
    Object? previousValue,
    Object? newValue,
  ) {
    print('{"provider": "${context.provider}", "newValue": "$newValue"}');
  }
}

void main() {
  runApp(
    ProviderScope(
      observers: [Logger()],
      child: const MyApp(),
    ),
  );
}

Naming providers

为provider命名

For clearer logs, give providers a name:

dart

final myProvider = Provider<int>((ref) => 0, name: 'MyProvider');

With code generation, a name is usually assigned automatically.

为了让日志更清晰，可为provider指定一个名称：

dart

final myProvider = Provider<int>((ref) => 0, name: 'MyProvider');

使用代码生成时，通常会自动分配名称。

Note on mutations

关于状态变更的注意事项

If state is mutated in place (e.g. a List with ref.notifyListeners),

previousValue

and

newValue

in didUpdateProvider may be the same reference. For distinct values, clone before mutating.

如果状态是原地修改的（例如使用ref.notifyListeners的List），didUpdateProvider中的

previousValue

和

newValue

可能指向同一个引用。若需要区分不同的值，请在修改前进行克隆。