Flutter

Question

我正在构建一个页面，动态生成一些视图。在我的例子中，显示的列表将根据用户输入进行更新（用作过滤器）。

使用动态呈现的文本小部件时一切正常，但是当我尝试切换到列或网格视图时，一切都出错了并且出现了以下错误

The following assertion was thrown building ServerGrid(dirty; state: _ServerGridState#59211289()):
I/flutter (14351): setState() or markNeedsBuild() called during build.
I/flutter (14351): This Overlay widget cannot be marked as needing to build because the framework is already in the
I/flutter (14351): process of building widgets. A widget can be marked as needing to be built during the build phase
I/flutter (14351): only if one of its ancestors is currently building. This exception is allowed because the framework
I/flutter (14351): builds parent widgets before children, which means a dirty descendant will always be built.
I/flutter (14351): Otherwise, the framework might not visit this widget during this build phase.
I/flutter (14351): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (14351):   Overlay([LabeledGlobalKey<OverlayState>#774312152]; state: OverlayState#252339409(entries:
I/flutter (14351):   [OverlayEntry#727022347(opaque: false; maintainState: false), OverlayEntry#1051156104(opaque:
I/flutter (14351):   false; maintainState: true), OverlayEntry#280497357(opaque: false; maintainState: false),
I/flutter (14351):   OverlayEntry#41791024(opaque: false; maintainState: true), OverlayEntry#444321361(opaque: false;
I/flutter (14351):   maintainState: false), OverlayEntry#717668788(opaque: false; maintainState: true)]))

这是我目前得到的代码，

ServerGrid 这是抛出错误的地方导入 'package:flutter/material.dart';

import'package:firebase_sandbox/models/server.dart';

class ServerGrid extends StatefulWidget {
  ServerGrid({Key key, this.servers}) : super(key: key);

  final servers;

  @override
  State createState() => new _ServerGridState();
}

class _ServerGridState extends State<ServerGrid> {

  showInfos(serv){
    showDialog(context: context, child: new AlertDialog(content: new Text(serv.toString())));
  }

  Widget buildServerTile(Server serv) {
    return new InkWell(
        onTap: showInfos(serv),
        child :
          new Column(
            children: [
                new CircleAvatar(child : new Image.network(serv.image)),
                new Text(
                  serv.name,
                  style : new TextStyle(fontWeight: FontWeight.bold),
                ),
                new Text(
                  serv.description,
                  style : new TextStyle(color : Colors.grey[500]),
                ),
            ],
          ),
    );
  }

   List<Widget> buildGrid() {
    var theGrid = <Widget>[];
    for(Server s in widget.servers) {
      theGrid.add(buildServerTile(s));
    }
    return theGrid;
  }

  @override
  Widget build(BuildContext context) {
    // return new Text("${widget.servers.toString()}"); //Working perfectly
    return new GridView(
              gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: 3,
              ),
               children: buildGrid(),
          );
  }
}

控制器调用视图进行更新：

  filter(value) {
    filteredList = _servers.where(
            (serv) =>
        serv.name.contains(value) || serv.tags
            .where((tag) => tag.contains(value))
            .length > 0
    ).toList();

    print(filteredList);
    setState(() {
      serverList = new ServerGrid(servers : filteredList);
    });
  }

一直在搜索，但我无法弄清楚构建 Gridview 时出了什么问题

Answer 1

您的 onTap 处理程序有问题。它试图在您的构建函数期间立即显示对话框，这是不允许的。

onTap: showInfos(serv),

将您的处理程序更改为函数：

onTap: () => showInfos(serv),

Answer 2

我使用了另一个有趣的解决方案。所以，这里发生的是它通知重建 UI，而 UI 已经在构建，这导致了错误。所以，我修复它的方法是将它放在 Future.delayed() 函数中，并给它一个小的持续时间，比如 1 毫秒。它的作用是稍后运行 notifylistener，您不会遇到任何问题。显然这不是正确的解决方法，但可以提供帮助

Flutter - 无法构建，因为 frawework 已经在构建

Flutter - Cannot build because the frawework is already building

dart