如何转换Future< List>列出来？ [英] How to convert Future<List> to List in flutter?

问题描述

我正在使用一个名为 search_widget 的插件。
此小部件的data参数带有一个列表。但是当我使用 sqlite 来获取数据时，我将其以 Future< List> 的形式保存。
有什么方法可以将 Future< List> 转换为 List ？
或任何其他使此工作正常进行的方法。

I am using a plugin for flutter called search_widget. The data parameter of this widget takes a list. But as I use sqlite for fetching data, I have it in Future<List> form. Is there any way I can convert Future<List> to List? Or any other way to get this working.

推荐答案

从 search_widget ，您需要在这样的小部件中使用 dataList ：

Borrowing the example from search_widget you need dataList in a widget like this:

SearchWidget<LeaderBoard>(
   dataList: list,
   textFieldBuilder: (TextEditingController controller, FocusNode focusNode) {
     return MyTextField(controller, focusNode);
   },
 )

当然，您可以像其他答案一样将 Future< List> 转换为 List 。但是您无法能够执行 dataList：等待_sqliteCall（）; ，因为 build

Sure, you can convert Future<List> into List like other answers suggest. But you won't be able to do dataList: await _sqliteCall(); because build methods are designed to be pure and sychronous.

在未来完成时，您将必须返回诸如进度指示器之类的东西。为此，您可以使用 FutureBuilder ：

While the Future completes you will have to return something like a progress indicator. For that you can use a FutureBuilder:

FutureBuilder<List<Leaderboard>>(
  future: _sqliteCall(),
  builder: (context, snapshot) {
    if (snapshot.hasData) {
      return SearchWidget<LeaderBoard>(
        dataList: snapshot.data,
        textFieldBuilder: (TextEditingController controller, FocusNode focusNode) {
          return MyTextField(controller, focusNode);
        },
      )
    }
    return CircularProgressIndicator();
  }
),

当然也可以使用 StatefulWidget 完成，您可以检查有关此问题的详细说明，本文。

Of course this can also be done with a StatefulWidget, you can check this article for a detailed explanation of the issue.

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