[英]Cannot update text with TextFormField
I want to add splash after user entered 2 numbers for day and 2 numbers for month.我想在用户输入 2 个日数和 2 个月数后添加飞溅。 The code below worked before but I don't know from which flutter version, it started behaving strangely.
下面的代码以前工作过,但我不知道从哪个 flutter 版本开始,它开始表现得很奇怪。
class MyCustomForm extends StatefulWidget {
@override
_MyCustomFormState createState() => _MyCustomFormState();
}
class _MyCustomFormState extends State<MyCustomForm> {
final _dobInputController = TextEditingController();
String _lastDobValue = '';
@override
void initState() {
super.initState();
_dobInputController.addListener(_onTextChange);
}
@override
void dispose() {
_dobInputController.dispose();
super.dispose();
}
_onTextChange() {
int length = _dobInputController.text.length;
if (_lastDobValue.length < length && (length == 2 || length == 5)) {
_dobInputController.text += '/';
_dobInputController.selection = TextSelection.fromPosition(TextPosition(offset: length + 1));
}
_lastDobValue = _dobInputController.text;
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
TextFormField(
controller: _dobInputController,
decoration: InputDecoration(
hintText: 'MM/DD/YYYY',
),
)
],
),
));
}
}
Just replace TextFormField
with TextField
, it will work properly again.只需将
TextFormField
替换为TextField
,它将再次正常工作。
We should use inputFormatters
instead to avoid inner loop since updating text using TextEditingController
will call itself and act strangely:我们应该使用
inputFormatters
来避免内部循环,因为使用TextEditingController
更新文本会调用自身并产生奇怪的行为:
TextFormField(
decoration: InputDecoration(
hintText: 'MM/DD/YYYY',
),
inputFormatters: [
TextInputFormatter.withFunction((oldValue, newValue) {
String newText = newValue.text;
int newTextLength = newText.length;
if (newValue.text.length > oldValue.text.length && (newTextLength == 2 || newTextLength == 5)) {
return TextEditingValue(
text: newText + '/',
selection: TextSelection.fromPosition(TextPosition(offset: newTextLength + 1)));
}
return newValue;
})
])
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