颤振错误：未定义的名称“上下文”

Question

当我尝试将我的颤振页面从 neighbourhoodList 推送到各个社区（例如 neighbourhoodlist_admirality）时收到一些错误。

在我的社区列表中，当用户点击相关社区时，我想导航到各个社区页面。由于我还没有建立单独的社区页面，我已经将它们链接到一个示例页面，即 NeighbourhoodAdmirality。

这是我的 neighbourhoodlist 页面代码：

import 'package:flutter/material.dart';
import 'indv_neighbourhoods/neighbourhoodlist_admirality.dart';

class NeighbourhoodList extends StatefulWidget {
  NeighbourhoodList({ this.name = "name"});
  final String name;

  @override
  _NeighbourhoodListState createState() => _NeighbourhoodListState();
}

class _NeighbourhoodListState extends State<NeighbourhoodList> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Neighbourhoods',
        ),
      ),
      body: _buildListView(context),
    );
  }

  ListView _buildListView(BuildContext context){
    return ListView.builder(
      itemCount: allNeighbourhoods.length,
      itemBuilder: (BuildContext content, int index) {
          NeighbourhoodList neighbourhoodlist = allNeighbourhoods[index];
          return NeighbourhoodListTile(neighbourhoodlist);
        });
  }
}

class NeighbourhoodListTile extends ListTile {
  NeighbourhoodListTile(NeighbourhoodList neighbourhoodlist)
      : super(
          title: Text(neighbourhoodlist.name),
          trailing: Icon(Icons.arrow_forward),
          onTap: (){
            Navigator.push(
              context, 
              MaterialPageRoute(builder: (context) => NeighbourhoodAdmiralty(neigh1)),
              );
          }
        );
}

List<NeighbourhoodList> allNeighbourhoods = [
  NeighbourhoodList(name: 'Admiralty'),
  NeighbourhoodList(name: 'Aljunied'),
  NeighbourhoodList(name: 'Ang Mo Kio'),

];

这是一个示例页面的代码，我想在每个单独的社区被引导时将我的邻居列表指向该页面。

import 'package:flutter/material.dart';

class NeighbourhoodAdmiralty extends StatefulWidget {
  final String neigh1;
  NeighbourhoodAdmiralty(this.neigh1);

  @override
  _NeighbourhoodAdmiraltyState createState() => _NeighbourhoodAdmiraltyState();
}

class _NeighbourhoodAdmiraltyState extends State<NeighbourhoodAdmiralty> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Admiralty"),
      ),
      body: Center(child: Text('This is the individual neighbourhood page'),
      ),
    );
  }
}

由于我还是一个初学者，我遇到了一些错误，并且有几个问题：

neighbourhoodlist.dart 上的错误 1：Navigator.push 下的“未定义名称 'context'” --> 不知道为什么会发生这种情况，因为我已经在上面的方法中传递了 BuildContext

neighbourhoodlist.dart 上的错误 2：Navigator.push 下的“未定义名称 'neigh1'” --> 我想将 neighbourhoodlist.dart 页面重定向到各个社区工作表，但我不确定我在这里传递了什么，我已经尝试过 'neigh1'（我在 neighbourhoodlist_admirality 中的变量）、'name' - NeighbourhoodList 中的变量和 'index' 0 中的变量 inNeighbourhoodListState 但到目前为止它们似乎都不起作用。

感谢您为解决此问题提供的所有帮助，并提前致谢！

Answer 1

当你这样做时

class NeighbourhoodListTile extends ListTile {
  NeighbourhoodListTile(NeighbourhoodList neighbourhoodlist)
      : super(
          title: Text(neighbourhoodlist.name),
          trailing: Icon(Icons.arrow_forward),
          onTap: (){
            Navigator.push(context, MaterialPageRoute(builder: (context) => NeighbourhoodAdmiralty(neigh1)));
          }
        );
}

您无法访问 onTap 中的 context，因为 Flutter 目前还没有为您提供。如果您需要 context，请改用 StatelessWidget，您可以在 build 方法中访问它：

class NeighbourhoodListTile extends StatelessWidget {
  final NeighbourhoodList neighbourhoodlist;

  const NeighbourhoodListTile(this.neighbourhoodlist);

  @override
  Widget build(BuildContext context) {
    //  Here's your context ^^^^^^^
    return ListTile(
      title: Text(neighbourhoodlist.name),
      trailing: Icon(Icons.arrow_forward),
      onTap: (){
        Navigator.push(context, MaterialPageRoute(
          builder: (context) => NeighbourhoodAdmiralty(neigh1)));
      }
    );
  }
}

---

至于您的第二个错误，此时也没有 neigh1 变量。我不知道你的逻辑是什么，但我想你想用neighbourhoodlist.name替换它：

class NeighbourhoodListTile extends StatelessWidget {
  final NeighbourhoodList neighbourhoodlist;

  const NeighbourhoodListTile(this.neighbourhoodlist);

  @override
  Widget build(BuildContext context) {
    return ListTile(
      title: Text(neighbourhoodlist.name),
      trailing: Icon(Icons.arrow_forward),
      onTap: (){
        Navigator.push(context, MaterialPageRoute(
          builder: (context) => NeighbourhoodAdmiralty(neighbourhoodlist.name)));
      }
    );
  }
}