如何在小部件中查找上下文？它是未定义的

Question

我一直在尝试找到一种方法来在“Widget CardUI”中放置导航，因为我希望它在用户单击时将其重定向到另一个页面。但是，当我尝试放置通常的 Navigator.push(context, MaterialPageRoute(builder: (context)=>PageName()));" 时，它告诉我上下文未定义。

  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          leading: IconButton(
              icon: Icon(Icons.arrow_back, color: Colors.white),
              onPressed: ()
              {Navigator.pop(context);
              Navigator.push(context, MaterialPageRoute(builder: (context)=>homepage()));}),
          title: Text("Creator's Club"),
          backgroundColor: Color(0xff2657ce),
          elevation: 0,),
        body: Container(
            padding: EdgeInsets.all(20),
            child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: <Widget>[
                  Text('Visual Arts', style: TextStyle(
                    color: Color(0xff2657ce),
                    fontSize: 27,
                  ),),
                  Text('Choose which course you want to study.', style: TextStyle(
                      color: Colors.black.withOpacity(0.6),
                      fontSize: 20
                  ),),
                  SizedBox(height: 10),
                  Expanded(
                    child: SingleChildScrollView(
                      child: Column(
                          children: <Widget>[
                            coursesList.length == 0 ? Center(child: Text("Loading...", style: TextStyle(fontSize: 15),)): ListView.builder(
                                scrollDirection: Axis.vertical,
                                shrinkWrap: true,
                                physics: const NeverScrollableScrollPhysics(),
                                itemCount: coursesList.length,
                                itemBuilder: (_, index) {
                                  return CardUI(coursesList[index].courseName, coursesList[index].teacher, coursesList[index].category);
                                }
                            )
                          ]
                      ),
                    ),
                  ),
                ]
            )
        )
    );
  }
}

Widget CardUI (String courseName, String teacher, String category){
      return Card(
        elevation: 1,
        margin: EdgeInsets.all(5),
        color: Color(0xffd3defa),
        child: Container(
            color: Colors.white,
            margin: EdgeInsets.all(1),
            padding: EdgeInsets.all(10),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Row(
                    children: <Widget>[
                      Container(
                        width: 50,
                        height: 50,
                        decoration: BoxDecoration(
                          color: Color(0xffd3defa),
                          borderRadius: BorderRadius.all(Radius.circular(17)),
                        ),
                        child: IconButton(
                          icon: Icon(
                            Icons.star_border_rounded,
                            color: Color(0xff2657ce),
                          ),
                        ),
                      ),
                      SizedBox(width: 15,),
                      Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: <Widget>[
                            Container(
                                child: InkWell(
                                  onTap: () {},
                                  child: Column(
                                    crossAxisAlignment: CrossAxisAlignment.start,
                                    children: <Widget>[
                                      Text(courseName,
                                          style: TextStyle(fontSize: 18)),
                                      SizedBox(height: 5),
                                      Text(teacher, style: TextStyle(
                                          fontSize: 15, color: Colors.grey)),
                                      SizedBox(height: 5),
                                    ],
                                  ),
                                )
                            )
                          ]
                      )
                    ]
                )
              ],
            )
        ),
      );
  }

此外，有没有办法在 Inkwell onTap 中设置 if else 条件？在我的代码中，从实时数据库中显示了一堆课程，我只想点击其中一个。在我当前的代码中，Inkwell 适用于所有正在显示的卡片，但我只希望它在一张上。除了使用 Inkwell，还有其他选择吗？

Answer 1

尝试调用

onPressed: () {
  Navigator.push(context, MaterialPageRoute(builder: (context)=>homepage()));
},

之前没有pop。