flutter - Navigator.push可以和Flutter三元一起使用吗

Question

我有一个包含四个选项卡的应用栏的页面。在其中一个选项卡上，我试图在构建方法中使用一个条件，以在条件为真时显示具有特定内容的自定义 ScrollView 。如果条件为假，我希望用户被导航到一个全新的页面，该页面只有一个 ListView 和它自己的不包含任何选项卡的应用程序栏。 Navigator.push 被用作三元组中的第二个条件会引发错误。我在下面代码中的目标类似于 if file == null 在 Safe Area 小部件中显示内容，否则导航到 UploadItemsFormPage。我一直无法弄清楚如何解决这个挑战。我试图删除很多代码以减少阅读量，但如果需要帮助，我可以提供更多代码。代码将被重构为不同的小部件，但我认为这会使问这个问题变得更加复杂，所以现在它都在一个类中。在此先感谢您的帮助。

class ShoppingAdminPage extends StatefulWidget {
  const ShoppingAdminPage({Key? key}) : super(key: key);

  @override
  State<ShoppingAdminPage> createState() => _ShoppingAdminPageState();
}

class _ShoppingAdminPageState extends State<ShoppingAdminPage> {
  final List<String> _tabs = <String>[
    TabNameString.upload,
    'Tab Two',
    'Tab Three',
    'Tab Four',
  ];

  TextEditingController descriptionController = TextEditingController();
  String productID = DateTime.now().microsecondsSinceEpoch.toString();
  TextEditingController priceController = TextEditingController();
  TextEditingController titleController = TextEditingController();
  bool isUploading = false;
  File? file;

  void clearImage() {
    setState(() {
      file = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    return AdaptiveLayoutScaffold(
      drawer: const SideSheet(),
      landscapeBodyWidget: Container(),
      portraitBodyWidget: BrandTabController(
        actions: const [
          BrandPopUpMenu(),
        ],
        numberOfTabs: _tabs.length,
        pageName: PageName.shoppingAdmin,
        tabBarView: TabBarView(children: [
          file == null
              ? SafeArea(
                  top: false,
                  bottom: false,
                  child: Builder(
                    builder: (BuildContext context) {
                      return CustomScrollView(
                        key: const PageStorageKey<String>(
                          TabNameString.upload,
                        ),
                        slivers: <Widget>[
                          SliverOverlapInjector(
                            handle:
                                NestedScrollView.sliverOverlapAbsorberHandleFor(
                              context,
                            ),
                          ),
                          SliverToBoxAdapter(
                            child: Column(
                              mainAxisAlignment: MainAxisAlignment.center,
                              children: <Widget>[
                                const SizedBox(
                                  height: 60.0,
                                ),
                                SvgPicture.asset(
                                  ImageUrlString.uploadItemSVG,
                                  height: 260.0,
                                ),
                                Padding(
                                  padding: const EdgeInsets.only(
                                    top: 20.0,
                                  ),
                                  child: ElevatedButton(
                                    onPressed: () {
                                      showDialog(
                                          context: context,
                                          builder: (context) {
                                            return BrandSimpleDialog(
                                              dialogTitle:
                                                  DialogString.itemImage,
                                              optionOneCallback: () async {
                                                Navigator.pop(context);
                                                XFile? pickedFile =
                                                    await ImagePicker()
                                                        .pickImage(
                                                  imageQuality: 85,
                                                  maxHeight: 675,
                                                  maxWidth: 960,
                                                  source: ImageSource.camera,
                                                );
                                                setState(() {
                                                  file = File(pickedFile!.path);
                                                });
                                              },
                                              optionOneText: DialogString
                                                  .captureWithCamera,
                                              optionTwoCallback: () async {
                                                Navigator.pop(context);
                                                XFile? pickedFile =
                                                    await ImagePicker()
                                                        .pickImage(
                                                  imageQuality: 85,
                                                  source: ImageSource.gallery,
                                                );
                                                setState(() {
                                                  file = File(pickedFile!.path);
                                                });
                                              },
                                              optionTwoText: DialogString
                                                  .selectFromGallery,
                                            );
                                          });
                                    },
                                    child: Text(
                                      ButtonString.uploadNewItems.toUpperCase(),
                                    ),
                                  ),
                                ),
                              ],
                            ),
                          ),
                        ],
                      );
                    },
                  ),
                )
              : UploadItemsFormPage(
                  contentImage: file as File,
                  descriptionController: descriptionController,
                  isUploading: isUploading,
                  onPressedClear: clearImage,
                  priceController: priceController,
                  titleController: titleController,
                ),
          Container(),
          Container(),
          Container(),
        ]),
        tabs: _tabs,
      ),
    );
  }
}

Answer 1

您可以在任何情况下使用三元运算符。假设在您的上述情况下(例如 file ==null 的任何真实条件)？(如果文件为 null 则做一些工作):Navigator.push( context, MaterialPageRoute(builder: (context) => Uploadimages()), ); (如果三元条件不正确，请进行更改)