当我滚动时，颤动表单数据消失 [英] flutter form data disappears when I scroll
问题描述
我有一个小部件，它有一个图像元素和表单元素的扩展listview，当我填写并滚动数据时，当它在图像后面滚动时，它们就会消失.当我调试时它不会引发任何错误，它发生在滚动到窗口小部件顶部图像后面的任何字段上.有什么想法吗?
I have a widget, that has an image element and and expanded listview of form elements that as I fill out and scroll the data disappears when it scrolls behind the image. It is not throwing any errors when I debug and it happens on any field that scrolls behind the image at the top of the widget. Any ideas?
@override
Widget build(BuildContext context) {
var _children = <Widget>[
new Center(
child: new Text(widget.prov.fname + widget.prov.lname,
style: new TextStyle(fontSize: 20.0, fontWeight: FontWeight.bold),
),
),
new Center(
child: new Container(
padding: new EdgeInsets.only(
left: 125.0, right: 125.0, bottom: 50.0),
child: new Image.network('http://$baseurl:8080/getimage/'+widget.prov.pic.assetName),
)
),
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 *',
),
onSaved: (String value) { referral.fname = value; },
validator: _validateName,
),
new TextFormField(
decoration: const InputDecoration(
icon: const Icon(Icons.person),
hintText: 'Last Name?',
labelText: 'Last Name *',
),
onSaved: (String value) { referral.lname = value; },
validator: _validateName,
),
new TextFormField(
decoration: const InputDecoration(
icon: const Icon(Icons.phone),
hintText: 'How to contact?',
labelText: 'Phone Number *',
prefixText: '+1'
),
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(
hintText: 'Tell us about patient',
helperText: 'It does not have to be detailed yet',
labelText: 'Referral Details',
),
maxLines: 5,
),
new _DateTimePicker(
labelText: 'DOB',
selectedDate: _fromDate,
selectDate: (DateTime date) {
setState(() {
referral.dob = date;
});
},
),
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 RefreshIndicator(
child: new ListView.builder(
itemBuilder: _itemBuilder,
itemCount: listcount,
),
onRefresh: _onRefresh,
),*/
];
return new Scaffold(
appBar: new AppBar(title: new Text("My Provider")),
body: new Column(
children: _children,
),
);
}
推荐答案
我认为问题是您没有保存输入到TextField中的值(例如，保存为状态).
从您的代码中，我假设您正在使用ListView.builder()来设置ListView.如文档所述，此方法仅呈现子级，在视野中.一旦将子级滚动到视图外，将其从ListView中删除，并且在将其滚动到视图中后才再次添加.因为删除了TextField，所以值也被删除了.
I think the problem is that you don't save the values which were put into the TextFields (to a state for example).
From your code I assume you are using the ListView.builder() to set up your ListView. This method, as stated in the documentation, renders only the children, which are in view. Once you scroll a child out of view, it is removed from the ListView and only added again, once you scroll it into view. Because the TextField is removed, the value is removed as well.
要永久保存值，我建议使用TextFields并将输入保存到 onChanged() 方法，或使用
To permanently have the value saved, I would advice to use TextFields and save the input to state in the onChanged() method of the TextField, or make use of TextEditingController.
这篇关于当我滚动时，颤动表单数据消失的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
