Flutter项目中如何缩短Riverpod依赖注入的冗长调用语句？

以下四种方案均为编译期语法糖实现，无额外运行时性能损耗，可根据场景组合使用：

1. 给BuildContext做扩展封装 #

直接将高频调用的Provider读取、甚至业务方法封装为BuildContext的扩展属性/方法，是最接近原生函数调用的实现方式：

// 全局扩展定义
extension AppServiceExt on BuildContext {
  // 封装Provider读取
  LocalServices get localServices => read(localServices);
  MasterSyncEventServices get masterSyncEventServices => read(masterSyncEventServices);

  // 可进一步封装高频调用的业务方法
  Future<void> addSyncEvent(SyncEvent syncEvent, String localId) => 
      masterSyncEventServices.addSyncEvent(syncEvent, localId);
  Future<void> editSale({required Sale sale, required String saleKey, required String userId}) =>
      localServices.editSale(sale: sale, saleKey: saleKey, userID: userId);
  Future<void> addSale(Sale sale, String userId) => localServices.addSale(sale, userId);
}

封装后你的示例代码可直接简化为：

if (saleKey != null) {
    await context.editSale(sale: updatedSale()!, saleKey: saleKey, userId: localID);
    await uuidBox.add(syncEvent.syncUUID);
    await context.addSyncEvent(syncEvent, localID);
} else {
    await context.addSale(updatedSale()!, localID);
    await uuidBox.add(syncEvent.syncUUID);
    await context.addSyncEvent(syncEvent, localID);
}

单句调用context.read(masterSyncEventServices).addSyncEvent(syncEvent, localID);可直接缩短为await context.addSyncEvent(syncEvent, localID);。

2. 作用域内提前缓存Provider实例 #

在方法执行开头统一读取需要用到的Provider实例存入变量，后续直接用变量调用，同时还能避免多次执行context.read的重复开销：

// 方法开头统一读取
final localServices = context.read(localServices);
final syncServices = context.read(masterSyncEventServices);

// 后续调用直接用变量
if (saleKey != null) {
    await localServices.editSale(sale: updatedSale()!, saleKey: saleKey, userID: localID);
    await uuidBox.add(syncEvent.syncUUID);
    await syncServices.addSyncEvent(syncEvent, localID);
} else {
    await localServices.addSale(updatedSale()!, localID);
    await uuidBox.add(syncEvent.syncUUID);
    await syncServices.addSyncEvent(syncEvent, localID);
}

3. 业务逻辑抽离到Notifier层 #

不要在UI层直接写跨服务的业务逻辑，将相关逻辑封装到对应功能的Notifier内部，UI层仅调用Notifier的暴露方法即可：

// Notifier层内部封装逻辑
class SaleNotifier extends Notifier<SaleState> {
  @override
  SaleState build() => SaleState();

  Future<void> saveSale(Sale? sale, String? saleKey, String localId, SyncEvent syncEvent) async {
    final localServices = ref.read(localServices);
    final syncServices = ref.read(masterSyncEventServices);
    if (saleKey != null) {
      await localServices.editSale(sale: sale!, saleKey: saleKey, userID: localId);
    } else {
      await localServices.addSale(sale!, localId);
    }
    await uuidBox.add(syncEvent.syncUUID);
    await syncServices.addSyncEvent(syncEvent, localId);
  }
}

UI层调用直接简化为：

await context.read(saleNotifier.notifier).saveSale(updatedSale(), saleKey, localID, syncEvent);

4. 优先使用ref替代context.read #

如果你使用的是Riverpod 2.0+版本，在ConsumerWidget、Notifier等支持ref的场景中，直接用ref.read替代context.read，本身就能缩短调用长度，配合上述封装效果更好。

内容的提问来源于stack exchange，提问作者RobbB