flutter - 更改BottomNavigationBar中的页面时，强制Flutter不会丢失数据

Question

我的flutter应用程序有一个bottomNavigationBar小部件，它实际上可以正常工作，所以...
问题是我将页面更改为另一页面后，我从API调用中丢失了数据，然后当我回来时，我必须再次对所有内容进行re-fetch!
避免这种情况的最佳方法是什么？
编码

// ...Some code...

class _HomeState extends State<Home> {
  List<wp.Post> posts = [];
  int _pageNumber = 1;

  Future<String> getPosts() async {
    var res = await fetchPosts(_pageNumber);
    setState(() {
      posts = res;
    });
    return "Success!";
  }

  // Get posts when app loads;
  @override
  void initState() {
    super.initState();
      this.getPosts();
  }

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: posts == null ? 0 : posts.length,
      itemBuilder: (BuildContext context, int index) {
        return buildPost(context, posts, index); //Building the posts list view
      },
    );
  }
}

Answer 1

您可以使用`AutomaticKeepAliveClientMixin”来保持页面状态。

class _HomeState extends State<Home> with AutomaticKeepAliveClientMixin { //<== add mixin
  List<wp.Post> posts = [];
  int _pageNumber = 1;

  @override
  bool get wantKeepAlive => true; //<== add this line 

  Future<String> getPosts() async {
    var res = await fetchPosts(_pageNumber);
    setState(() {
      posts = res;
    });
    return "Success!";
  }

  // Get posts when app loads;
  @override
  void initState() {
    super.initState();
      this.getPosts();
  }

  @override
  Widget build(BuildContext context) {

    super.build(context); // <== add this line
    return ListView.builder(
      itemCount: posts == null ? 0 : posts.length,
      itemBuilder: (BuildContext context, int index) {
        return buildPost(context, posts, index); //Building the posts list view
      },
    );
  }
}