Flutter 颤振-子类小部件与包装它
我有一些颤振代码,如下所示:Flutter 颤振-子类小部件与包装它,flutter,Flutter,我有一些颤振代码,如下所示: class InputWithValidation extends StatelessWidget { InputWithValidation({this.fieldName, this.accessor}); final String fieldName; final ModelAccessor accessor; Widget build(context) { var elem = FooDataDictionary.of(cont
class InputWithValidation extends StatelessWidget {
InputWithValidation({this.fieldName, this.accessor});
final String fieldName;
final ModelAccessor accessor;
Widget build(context) {
var elem = FooDataDictionary.of(context).dataElement(fieldName);
return Container(
margin: EdgeInsets.all(inputMargin),
child: TextFormField(
keyboardType: elem.keyboardType,
initialValue: elem.getAsString(accessor),
autovalidate: true,
validator: elem.validate,
onSaved: (val) {
elem.setFromString(accessor, val);
},
decoration: InputDecoration(
hintText: FooLocalizations.of(context).hint(fieldName),
labelText: FooLocalizations.of(context).label(fieldName)),
));
}
}
我想重构它以提取TextFormField,这样我就可以在其他地方重复使用它,而无需硬编码边距的使用
我的第一次尝试是写:
class DataElementTextFormField extends TextFormField
{
final DataElement dataElement;
final ModelAccessor accessor;
DataElementTextFormField(this.dataElement, this.accessor) :
super(
keyboardType: dataElement.keyboardType,
initialValue: dataElement.getAsString(accessor),
autovalidate: true,
validator: dataElement.validate,
onSaved: (val) {
dataElement.setFromString(accessor, val);
},
decoration: InputDecoration(
hintText: FooLocalizations.of(context).hint(fieldName),
labelText: FooLocalizations.of(context).label(fieldName)),
);
}
但是,hintText
/labelText
行不再工作,因为它们需要BuildContext
来获得正确的本地化实例。这让我一时不知所措,因为我不确定这样子类化小部件的正确方法
所以我的问题有两点:
StatefulWidget子类化并允许访问BuildContext
的正确方法是什么
一般来说,组合优于继承,即使对于SDK的小部件也是如此。如果继承,您确实需要深入研究父类并确保遵守所有协议。使用composition,您可以简单地查看发布的API,并遵循其中的规则