Flutter:在布局期间对象被赋予无限大小

Question

我正在解决一个问题，我收到错误“ 布局期间对象被赋予无限大小”
和
“这可能意味着它是一个试图尽可能大的渲染对象，但它被放置在另一个渲染对象中，允许其子项选择自己的大小。”。
我明白这意味着什么，但不知道我如何仍然可以保留我当前的小部件树 响应式 (它在运行时呈现，所以对于前端用户来说似乎没有问题)同时仍然解决这个问题。目前我没有设置某些东西的大小来保持响应，和 如果可能，希望避免小部件的硬编码大小 .
非常感谢任何正确方向的帮助或指示:)
这是我当前的代码:

    class EditArtikel extends StatefulWidget {
  final String path;

  EditArtikel({this.path});

  @override
  _EditArtikelState createState() => _EditArtikelState(path: path);
}

class _EditArtikelState extends State<EditArtikel> {
  final String path;

  _EditArtikelState({this.path});

  final titleController = TextEditingController();
  final subtitleController = TextEditingController();
  final authorController = TextEditingController();
  final textController = TextEditingController();

  File imageFile;

  List<DropdownMenuItem<dynamic>> dropdownMenuItemFromList() {
    List<DropdownMenuItem<dynamic>> itemsList = [];
    for (var i = 1; i < currentTags.length; i++) {
      itemsList.add(new DropdownMenuItem(
        child: Text(currentTags[i]),
        value: currentTags[i],
      ));
    }
    return itemsList;
  }

  var _selectedValue = "";

  @override
  Widget build(BuildContext context) {
    final isAdmin = Provider.of<bool>(context);
    var pathElements = path.split('/');
    final String artikelID = pathElements[3];
    List<DropdownMenuItem<dynamic>> items = dropdownMenuItemFromList();

    if (isAdmin == true) {
      return LayoutBuilder(
        builder: (context, constraint) {
          return GlobalScaffold(
            body: Container(
              height: constraint.maxHeight,
              child: SingleChildScrollView(
                child: StreamBuilder<ArtikelData>(
                    stream:
                        DatabaseService(pathID: artikelID).artikelByArtikelID,
                    builder: (context, snapshot) {
                      if (snapshot.hasData) {
                        titleController.text == ""
                            ? titleController.text = snapshot.data.title
                            : titleController.text;

                        subtitleController.text == ""
                            ? subtitleController.text = snapshot.data.subtitle
                            : subtitleController.text;

                        authorController.text == ""
                            ? authorController.text = snapshot.data.author
                            : authorController.text;

                        textController.text == ""
                            ? textController.text = snapshot.data.text
                            : textController.text;

                        _selectedValue == ""
                            ? _selectedValue =
                                currentTags.contains(snapshot.data.tags)
                                    ? snapshot.data.tags
                                    : currentTags[1]
                            : _selectedValue = _selectedValue;

                        FirebaseStorageImage fbImage = new FirebaseStorageImage(
                          fileName: artikelID,
                          storageLocation: fbRefArtiklarImages,
                        );

                        return Container(
                          color: primaryColor,
                          padding: EdgeInsets.symmetric(
                              horizontal: 20, vertical: 15),
                          child: Column(
                            mainAxisAlignment: MainAxisAlignment.spaceBetween,
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Column(
                                crossAxisAlignment: CrossAxisAlignment.start,
                                children: <Widget>[
                                  GradientHeading(
                                    large: true,
                                    text: "Redigera artikel",
                                  ),
                                  SizedBox(height: 15),
                                  CustomTextFormField(
                                    labelText: "Rubrik",
                                    controller: titleController,
                                  ),
                                  CustomTextFormField(
                                    labelText: "Underrubrik",
                                    controller: subtitleController,
                                  ),
                                  Padding(
                                    padding: EdgeInsets.only(bottom: 7),
                                    child: DropdownButtonFormField(
                                      decoration: customInputDecoration("Tags"),
                                      value: _selectedValue,
                                      isDense: true,
                                      onChanged: (value) {
                                        setState(() {
                                          _selectedValue = value;
                                        });
                                      },
                                      items: items,
                                    ),
                                  ),
                                  CustomTextFormField(
                                    labelText: "Skriven av",
                                    controller: authorController,
                                  ),
                                  CustomTextFormField(
                                    labelText: "Text",
                                    multiline: true,
                                    controller: textController,
                                  ),
                                  NormalButton(
                                    text: "Ladda upp ny bild",
                                    outlined: true,
                                    outlinedBgColor: primaryColor,
                                    onPressed: () async {
                                      FocusScope.of(context).unfocus();
                                      imageFile = await ChooseImage()
                                          .chooseImageFromGallery();
                                      setState(() {});
                                    },
                                  ),
                                  ConditionalBuilder(
                                    condition: imageFile == null,
                                    ifTrue: NormalButton(
                                      text: "Ta bort originalbild",
                                      shouldOverideColor: true,
                                      overriddenColor: redWarningColor,
                                      onPressed: () async {
                                        FocusScope.of(context).unfocus();
                                        showDialog(
                                          context: context,
                                          barrierDismissible: true,
                                          builder: (_) => AlertDialog(
                                            content: Text(
                                                "Vill du radera originalbilden?"),
                                            actions: <Widget>[
                                              FlatButton(
                                                child: Text("Avbryt"),
                                                onPressed: () {
                                                  Navigator.of(context).pop();
                                                },
                                              ),
                                              FlatButton(
                                                child: Text("Radera"),
                                                onPressed: () async {
                                                  await StorageService()
                                                      .deleteArtikelImageToStorage(
                                                          artikelID);
                                                  setState(() {});
                                                  Navigator.of(context).pop();
                                                },
                                              ),
                                            ],
                                          ),
                                        );
                                      },
                                    ),
                                  ),
                                  ConditionalBuilder(
                                    condition: imageFile != null,
                                    ifTrue: NormalButton(
                                      text: "Ta bort bild",
                                      shouldOverideColor: true,
                                      overriddenColor: redWarningColor,
                                      onPressed: () {
                                        FocusScope.of(context).unfocus();
                                        imageFile = null;
                                        setState(() {});
                                      },
                                    ),
                                  ),
                                  ConditionalBuilder(
                                    condition: imageFile != null,
                                    ifTrue: imageFile != null
                                        ? Image(
                                            image: FileImage(imageFile),
                                          )
                                        : Container(),
                                    ifFalse: fbImage,
                                  ),
                                  SizedBox(height: 40),
                                ],
                              ),
                              NormalButton(
                                text: "Publisera ändringar",
                                onPressed: () async {
                                  if (titleController.text != "" &&
                                      subtitleController.text != "" &&
                                      authorController.text != "" &&
                                      textController.text != "") {
                                    DatabaseService().editArtikel(
                                      artikelID,
                                      titleController.text,
                                      subtitleController.text,
                                      _selectedValue,
                                      authorController.text,
                                      textController.text,
                                      imageFile,
                                    );
                                    Navigator.pop(context);
                                  } else {
                                    showDialog(
                                      context: context,
                                      barrierDismissible: true,
                                      builder: (_) => AlertDialog(
                                        content:
                                            Text("Du måste fylla i alla fält"),
                                        actions: <Widget>[
                                          FlatButton(
                                            child: Text("OK"),
                                            onPressed: () {
                                              Navigator.of(context).pop();
                                            },
                                          )
                                        ],
                                      ),
                                    );
                                  }
                                },
                              ),
                            ],
                          ),
                        );
                      } else {
                        return LoadingWidget();
                      }
                    }),
              ),
            ),
          );
        },
      );
    } else {
      return GlobalScaffold(
        body: Center(
          child: Text("Du har inte tillgång till den här sidan"),
        ),
      );
    }
  }
}

这是错误日志:

Answer 1

从我可以看到的地方，您遇到了问题，因为您正在插入 StreamBuilder内SingleChildScrollView它具有无限的高度可以增长，并且 StreamBuilder询问他 parent 的高度。
StreamBuilder需要一个具有固定大小的父级，以便他可以了解他有多少空间来渲染他的 child 。

你需要做的是把SingleChildScrollView里面Container 具有给定大小 (您可以将所有主体放在 LayoutBuilder 中，并使用 constrains.maxHeight 作为容器的高度，因此 SingleChildScrollView 知道其大小)。

像这样:(因为我没有你的小部件，我无法运行这段代码......所以也许缺少一些括号)

我希望这有帮助!

return GlobalScaffold(
       body: LayoutBuilder(
         builder: (ctx, constrains){
           return GlobalScaffold(
      body: Container(
        height: constrains.maxHeight,
        child: SingleChildScrollView(
          child: Container(
            padding: EdgeInsets.symmetric(horizontal: 20, vertical: 15),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                GradientHeading(text: "Guider", large: true),
                ConditionalBuilder(
                  condition: isAdmin,
                  ifTrue: Column(
                    children: <Widget>[
                      NormalButton(
                        text: "Skapa ny guide",
                        onPressed: () {
                          Navigator.pushNamed(context, createNewArtikelRoute);
                        },
                      ),
                      NormalButton(
                        text: "Lägg till ny kategori",
                        outlined: true,
                        onPressed: () {},
                      ),
                    ],
                  ),
                ),
                SizedBox(height: 10),
                StreamBuilder<List<GuiderCategoriesData>>(
                  stream: DatabaseService().guiderCategoriesByPopularity,
                  builder: (context, snapshot) {
                    if (snapshot.connectionState == ConnectionState.active) {
                      return GuiderCategories(
                        snapshot: snapshot,
                        numberOfCategories: snapshot.data.length,
                      );
                    } else if (!snapshot.hasData) {
                      return GuiderCategories(
                        hasNoCategories: true,
                      );
                    } else {
                      return LoadingWidget();
                    }
                  },
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
  )
  );