使用 Navigator.push() 时"Infinite loop"

Question

我尝试使用Navigator.push()方法来加载另一个页面，但是当我这样做时，它在页面上导航时会给我抛出错误，然后它重新启动页面加载并向我显示错误，然后再次加载，再次错误...

这是导航的代码：

return Future.delayed(Duration.zero, (){
Navigator.of(context).push(MaterialPageRoute(builder: (context) => UserProfilePage(id, cookies)));
});

其中id是我的用户 ID，cookies是字符串列表。

抛出的错误是：

范围

错误(索引(：无效值：有效值范围为空：0 另请参阅：https://flutter.dev/docs/testing/errors

无效参数 另请参阅：https://flutter.dev/docs/testing/errors

以下是到达用户配置文件页面时调用的方法：

_getUserProfile(BuildContext context, String userId) async
{
await HibooksApiController.getUserInfo(userId).then((response) {
setState(() {
var resultApi = json.decode(response.body);
User result = User.fromJson(resultApi);
user = result;
});
});
for (var friend in user.friends) {
_getFriendProfile(context, friend.id, friends);
}
}
_getFriendProfile(BuildContext context, String friendId, List<User> friends) async
{
await HibooksApiController.getUserInfo(friendId).then((response) {
setState(() {
var resultApi = json.decode(response.body);
User result = User.fromJson(resultApi);
friends.add(result);
});
});
}
_getLibraries(BuildContext context, String userId) async
{
await HibooksApiController.getLibraries(userId).then((response){
setState(() {
var resultApi = json.decode(response.body);
for (var item in resultApi) {
Library library = Library.fromJson(item);
libraries.add(library);
}
});
});
}

Answer 1

@MarianoZorrilla我使用我找到的示例实现了一个片段管理器，这是交互：

_getDrawerItemWidget(int pos){
switch (pos) {
// SIDEBAR
case 0:
return new Text("Nous");
case 1:
return new Text("Paramètes");
case 2:
return new Text("Langue");
case 3:
return new Text("Dictionnaire");
case 4:
return new Text("FAQ");
case 5:
return new Text("Politique de confidentialité");
// --- HERE IS MY NAVIGATION PROBLEM --- //
case 6:
return Future.delayed(Duration.zero, (){
Navigator.of(context).push(MaterialPageRoute(builder: (context) => UserProfilePage(id, cookies)));
});
// --- //
case 7:
return new Text("Informations du compte");
case 8:
return new Text("Mes Favoris");
case 9:
return Future.delayed(Duration.zero, () => Navigator.push(context, MaterialPageRoute(builder: (context) => LoginPage())));
//BOTTOM NAVIGATION BAR
case 10:
return new AccueilFragment(id);
case 11:
return new LibraryFragment(id, cookies);
case 12:
return new ChatFragment(id, cookies);
case 13:
return new MatchFragment(id, cookies);
case 14:
return new Text("Événements");

default:
return new Text("Error");
}
}

方法：

_onSelectItem(int drawerIndex) {
setState(() => _selectedDrawerIndex = drawerIndex);
Navigator.of(context).pop(); // close the drawer
}

实现：

var drawerOptions = <Widget>[];
drawerOptions.add(
new SizedBox(
height: 80,
width: 350,
child: new DrawerHeader(
child: Text("Outils", style: TextStyle(fontFamily: "SFProDisplay")),
decoration: BoxDecoration(color: Color.fromRGBO(247, 247, 247, 1.0)),
),
)
);
for (var i = 0; i <= 5; i++) {
var d = widget.drawerItems[i];
drawerOptions.add(
new ListTile(
leading: new SizedBox(child: d.icon,),
title: new Text(d.title, style: TextStyle(fontFamily: "SFProDisplay")),
selected: i == _selectedDrawerIndex,
onTap: () => _onSelectItem(i),
)
);
}
drawerOptions.add(
new SizedBox(
height: 80,
width: 350,
child: new DrawerHeader(
child: Text("Profil", style: TextStyle(fontFamily: "SFProDisplay")),
decoration: BoxDecoration(color: Color.fromRGBO(247, 247, 247, 1.0)),
),
)
);
for(var j = 6; j <= 9; j++)
{
var d2 = widget.drawerItems[j];
drawerOptions.add(
new ListTile(
leading: new SizedBox(child: d2.icon,),
title: new Text(d2.title, style: TextStyle(fontFamily: "SFProDisplay")),
selected: j == _selectedDrawerIndex,
onTap: () => _onSelectItem(j),
)
);
}
for (var i = 10; i < widget.drawerItems.length; i++) {
var d = widget.drawerItems[i];
navbarOptions.add(
new BottomNavigationBarItem(
icon: new SizedBox(child: d.icon,),
title: Text(d.title),
)
);
}
if(navbarOptions.length != 0)
{
for(var z = navbarOptions.length; z > 5; z--)
{
navbarOptions.removeLast();
}
}

在我的小部件构建(( 中调用：

return new Scaffold(
appBar: new AppBar(
leading: Builder(builder: (BuildContext context) {
return new GestureDetector(
onTap: (){
Scaffold.of(context).openDrawer();
},
child: Material(
shape: CircleBorder(),
child: ClipOval(
child: FadeInImage(
placeholder: new ExactAssetImage("assets/Pictogramme-fond-blanc.png", scale: 4.5), 
image: NetworkImage(user.image.url), 
height: 50, 
width: 50, 
fit: BoxFit.cover,
),
),
)
);
}),
title: Text(
user.name.first != "" || user.name.last != "" ? "${user.name.first} ${user.name.last[0]}." : "${user.username}", 
style: TextStyle(color: Colors.black),
),
backgroundColor: Color(0xFFFFFFFF),
),
drawer: new Drawer(
child: new SingleChildScrollView(
child: new Column(
children: <Widget>[
new Column(children: drawerOptions),
],
),
),
),
body: _getDrawerItemWidget(_selectedDrawerIndex),
bottomNavigationBar: BottomNavigationBar(
items: navbarOptions,
currentIndex: _selectedNavbarIndex,
selectedItemColor: hibooks,
onTap: _onItemTapped,
),
);

此外，所有这些方法在我开发它们时都有效，但是当我将 Flutter 升级到版本"1.12.13+hotfix.5"时，错误就开始了。

Answer 2

好的，我找到了，1.12.13 版本的 Flutter 存在问题，当我将 Flutter SDK 升级到 1.15 时，它解决了我的问题。

谢谢！