如何从Flutter中获取FutureProvider的数据 [英] How to get data from the FutureProvider in flutter

问题描述

我正在尝试在使用Provider管理的flutter应用程序中实现本地数据库支持，现在我想使数据检索服从状态管理模式，但是我一直失败。

I'm trying to implement local database support in my flutter app which is being managed using Provider, now I want to make the retrieving of data obey the state management pattern, but I've been failing to.

我试图创建一个传统的Provider来实现此目的，但是应用程序陷入了对数据库的请求循环中，因此在进行一些搜索之后，我找到了FutureProvider，但是我找不到如何从正在加载的数据中获取快照

I've tried to make a traditional Provider to achieve this but the app got stuck in a loop of requests to the database, so after some search I found the FutureProvider, but I cant find how can I get a snapshot from the data being loaded

class _ReceiptsRouteState extends State<ReceiptsRoute> {
  List<Receipt> receipts = [];

  @override
  Widget build(BuildContext context) {
    return FutureProvider(
      initialData: List(),
      builder: (_){
        return DBProvider().receipts().then((result) {
          receipts = result;
        });
      },
      child: Scaffold(
        appBar: AppBar(
          title: Text(AppLocalizations.of(context).history),
        ),
        body: Container(
          child: ListView.builder(
            itemBuilder: (context, position) {
              final item = receipts[position];
              return ListTile(
                title: Text(item.date),
              );
            },
          ),
        ),
      ),
    );
  }
}

现在我的应用程序正在按我的方式运行，但没有如何运行，我使用FutureBuilder直接从数据库中获取数据，但我知道它应该通过提供程序提供，因此我想使其正确

now my app is running as I want but not as how it should run, I used FutureBuilder to get the data from the database directly but I know it should come through the provider so I want to make it right

推荐答案

FutureProvider 公开了 builder返回的 Future 的结果/ code>为其后代。

FutureProvider exposes the result of the Future returned by builder to its descendants.

因此，使用以下 FutureProvider ：

FutureProvider<int>(
  initialData: 0,
  builder: (_) => Future.value(42),
  child: ...
)

可以通过以下方式获取当前值：

it is possible to obtain the current value through:

Provider.of<int>(context)

或：

Consumer<int>(
  builder: (context, value, __) {
    return Text(value.toString());
  }
);

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