Flutter渲染索引堆栈对象在布局期间被赋予了无限大小

Question

Flutter渲染索引堆栈对象在布局期间被赋予了无限大小

flutterdartlayoutflutter-layoutflutter-widget

5

我正在解决这个 DropDownItem 框错误，一切似乎都可以工作，但在加载时弹出黄色越界。尝试了几次但无法解决。以下是我的 Widget 代码。

@override
Widget build(BuildContext context) {
    var _children = <Widget>[
      !_createNew ? _referrerPractice() : _referrerCreate(),
    ];
    return new Scaffold(
        appBar: new AppBar(
          title: new Text(widget.title),
        ),
        body: new Column(
          mainAxisSize: MainAxisSize.max,
          children: _children,
        ));
  }

我将其用作其中一个函数。

Widget _referrerPractice() {
assert(!_createNew);
return new Form(
  key: _formKey2,
  child: new Expanded(
    child: new ListView(
      padding: const EdgeInsets.symmetric(horizontal: 16.0),
      children: <Widget>[
        new InputDecorator(
          decoration: const InputDecoration(
            labelText: 'Referrer Practice',
            hintText: 'Choose Referrer Practice or choose new',
          ),
          isEmpty: _referPractice == null,
          child: new DropdownButton<String>(
            value: _referPractice,
            isDense: true,
            onChanged: (String newValue) {
              setState(() {
                _referPractice = newValue;
              });
            },
            items: practicelist.map((Map value) {
              return new DropdownMenuItem<String>(
                value: value['id'].toString(),
                child: new Text(value['name']),
              );
            }).toList(),
          ),
        ),
        new RaisedButton(
            child: new Text('Start'), onPressed: _startReferrer),
      ],
    ),
  ),
);

看起来在另一个页面上它能够工作，而且我没有使用函数来填充小部件，只是一个常规的窗口部件变量，但似乎应该与结构相同。

你有什么想法？这是一个DropDownButton，但对于其他功能也有一个DropDownButton，并且在生成的页面上也会出现这种情况。

编辑********** 这是可行的代码

final List<String> _allTypeAppt = <String>['Elective OP', 'Hospital Transfer', 'Phone Consult'];

new Form(
      key: _formKey,
      autovalidate: _autovalidate,
      onWillPop: _warnUserAboutInvalidData,
      child: new Expanded(
          child: new ListView(
            padding: const EdgeInsets.symmetric(horizontal: 16.0),
            children: <Widget>[
              new TextFormField(
                decoration: const InputDecoration(
                  icon: const Icon(Icons.person),
                  hintText: 'First Name?',
                  labelText: 'First Name *',
                ),
                controller: _fnameController,

                onSaved: (String value) { referral.fname = value; },
                validator: _validateName,
              ),

              new TextFormField(
                decoration: const InputDecoration(
                  icon: const Icon(Icons.person),
                  hintText: 'Last Name?',
                  labelText: 'Last Name *',
                ),
                controller: _lnameController,
                onSaved: (String value) { referral.lname = value; },
                validator: _validateName,
              ),

              new _DateTimePicker(
                labelText: 'DOB',
                selectedDate: _fromDate,
                selectDate: (DateTime date) {
                  setState(() {
                    _fromDate = date;
                  });
                },
              ),

              new TextFormField(
                decoration: const InputDecoration(
                    icon: const Icon(Icons.phone),
                    hintText: 'How to contact?',
                    labelText: 'Phone Number *',
                ),
                controller: _phoneController,
                keyboardType: TextInputType.phone,
                onSaved: (String value) { referral.contact = value; },
                validator: _validatePhoneNumber,
                // TextInputFormatters are applied in sequence.
                /*inputFormatters: <TextInputFormatter> [
                  WhitelistingTextInputFormatter.digitsOnly,
                  // Fit the validating format.
                  _phoneNumberFormatter,
                ],*/
              ),

              new TextFormField(
                decoration: const InputDecoration(
                  icon: const Icon(Icons.phone),
                  hintText: 'Alt contact?',
                  labelText: 'Alt Phone Number *',
                ),
                controller: _altPhoneController,
                keyboardType: TextInputType.phone,
                onSaved: (String value) { referral.altcontact = value; },
                validator: _validatePhoneNumber,
                // TextInputFormatters are applied in sequence.
                /*inputFormatters: <TextInputFormatter> [
                  WhitelistingTextInputFormatter.digitsOnly,
                  // Fit the validating format.
                  _phoneNumberFormatter,
                ],*/
              ),

              new TextFormField(
                decoration: const InputDecoration(
                  icon: const Icon(Icons.email),
                  hintText: 'Patien Email?',
                  labelText: 'Patient Email *',
                ),
                controller: _emailController,
                onSaved: (String value) { referral.altcontact = value; },
                //validator: _validatePhoneNumber,
                // TextInputFormatters are applied in sequence.
                /*inputFormatters: <TextInputFormatter> [
                  WhitelistingTextInputFormatter.digitsOnly,
                  // Fit the validating format.
                  _phoneNumberFormatter,
                ],*/
              ),

              new TextFormField(
                decoration: const InputDecoration(
                  hintText: 'Tell us about patient',
                  helperText: 'It does not have to be detailed yet',
                  labelText: 'Referral Details',
                ),
                controller: _detailsController,
                maxLines: 5,
              ),

              new InputDecorator(
                decoration: const InputDecoration(
                  labelText: 'Type of Appointment',
                  hintText: 'Choose an Appointment Type',
                ),
                isEmpty: _typeAppt == null,
                child: new DropdownButton<String>(
                  value: _typeAppt,
                  isDense: true,
                  onChanged: (String newValue) {
                    setState(() {
                      _typeAppt = newValue;
                    });
                  },
                  items: _allTypeAppt.map((String value) {
                    return new DropdownMenuItem<String>(
                      value: value,
                      child: new Text(value),
                    );
                  }).toList(),
                ),
              ),

              new RaisedButton(
                child: new Text('Submit Referral'),
                onPressed: _submitData,
              ),

            ],

          )
      )
  ),

- Robert

1

我不是很明白你的问题，你能否更清楚地表达一下？你遇到了什么错误？它出现在哪里？请尽量清晰地解释问题。问题是什么？ - Shady Aziza

你可以展示一下在另一页有效的代码吗？ - Shady Aziza

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Shady Aziza · Accepted Answer

我已经复现了你的问题，但是不确定为什么你要以这种方式构建布局。你将你的DropDownButton作为InputDecorator的child属性来使用，这是可以的。然而，它会抛出一个错误，因为DropDownMenuItem溢出了你的InputDecorator。换句话说，你不仅仅是将DopDownButton放在InputDecorator中，还有你的items也在同一个空间内尝试被包含。因此，Flutter不知道如何在InputDecorator所提供的空间内定位items列表。

我真的很困惑你正在尝试构建什么样的布局，你为什么需要一个 Form 和一个 InputDecorator？

也许提供一些设计选择的背景信息，我们可以更好地帮助你。

我创建了一个更简单的布局，使用Row和TextField小部件，这可能有所帮助。

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _mySelection;
  String _text = "Choose";
   List<Map> _myJson = [
    {"id": "ID 1310012", "name": "Newcommer"}, {"id": "ID 0000TEMP", "name": "Temp"}];

  Widget _children() {
    TextEditingController _controller = new TextEditingController(text: _text);
    return  new Expanded(child: new ListView(
            padding: const EdgeInsets.symmetric(horizontal: 16.0),
            children: <Widget>[
              new Container (
        child: new Row(
                  children: <Widget>[
                    new Expanded(
                      child: new TextField(
                        controller: _controller,
                      ),
                    ),
                    new DropdownButton(
                      isDense: true,
                      value: _mySelection,
                      items: _myJson.map((Map map) {
                        return new DropdownMenuItem<String>(
                          value: map["id"],
                          child: new Text(
                            map["name"],
                          ),
                        );
                      }).toList(),
                      onChanged: (String newValue) {
                        setState(() {
                          _mySelection = newValue;
                          _text = newValue;
                        });
                      })
              ],),),
              new RaisedButton(
                  child: new Text('Start'), onPressed: null),

            ]
        ));
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: new Text("Test")),
      body:  new Column(
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
           _children(),
        ],
      ),
    );
  }
}