TextField requires a MaterialLocalizations widget
Summary
#Instances of TextField
must have a
MaterialLocalizations
present in the widget tree.
Trying to instantiate a TextField
without the proper localizations
results in an assertion such as the following:
No MaterialLocalizations found.
TextField widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.
The material library uses Localizations to generate messages, labels, and abbreviations.
To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to
include them automatically, or add a Localization widget with a MaterialLocalizations delegate.
The specific widget that could not find a MaterialLocalizations ancestor was:
TextField
Context
#If the TextField
descends from a MaterialApp
, the
DefaultMaterialLocalizations
is already instantiated
and won't require any changes to your existing code.
If the TextField
doesn't descend from MaterialApp
,
you can use a Localizations
widget to
provide your own localizations.
Migration guide
#If you see an assertion error, make sure that
locale information is available to the TextField
,
either through an ancestor MaterialApp
(that automatically provides Localizations
), or
by creating your own Localizations
widget.
Code before migration:
import 'package:flutter/material.dart';
void main() => runApp(Foo());
class Foo extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MediaQuery(
data: const MediaQueryData(),
child: Directionality(
textDirection: TextDirection.ltr,
child: Material(
child: TextField(),
),
),
);
}
}
Code after migration (Providing localizations using the MaterialApp
):
import 'package:flutter/material.dart';
void main() => runApp(Foo());
class Foo extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Material(
child: TextField(),
),
);
}
}
Code after migration (Providing localizations via the Localizations
widget):
import 'package:flutter/material.dart';
void main() => runApp(Foo());
class Foo extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Localizations(
locale: const Locale('en', 'US'),
delegates: const <LocalizationsDelegate<dynamic>>[
DefaultWidgetsLocalizations.delegate,
DefaultMaterialLocalizations.delegate,
],
child: MediaQuery(
data: const MediaQueryData(),
child: Directionality(
textDirection: TextDirection.ltr,
child: Material(
child: TextField(),
),
),
),
);
}
}
Timeline
#Landed in version: 1.20.0-1.0.pre
In stable release: 1.20
References
#API documentation:
TextField
Localizations
MaterialLocalizations
DefaultMaterialLocalizations
MaterialApp
- Internationalizing Flutter apps
Relevant PR:
除非另有说明,本文档之所提及适用于 Flutter 的最新稳定版本,本页面最后更新时间: 2024-10-09。 查看文档源码 或者 为本页面内容提出建议。