Flutter-更改SearchDelegate的搜索提示文本

Question

在SearchDelegate的当前实现中，没有任何选项可以更改提示文本。当查询为空时，搜索屏幕将在查询字段中显示“搜索” 作为提示文本。

当前在第395行定义提示文本，如下所示：

final String searchFieldLabel = MaterialLocalizations.of(context).searchFieldLabel;

但是有一个existing issue to this subject reported。

我无法为此提出任何解决方案。 您知道该问题的任何解决方法吗？

Answer 1

当前SearchDelegate具有可选成员“ searchFieldLabel”，用于指定搜索字段的标签。 它应该看起来像这样：

  @override
  String get searchFieldLabel => 'custom label';

Answer 2

有一个解决方法，可以创建您自己的DefaultMaterialLocalizations类并将其传递到MaterialApp小部件中：

void main() => runApp(SearchApp());

class SearchApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: [
        CustomLocalizationDelegate(),
      ],
      home: Scaffold(
        appBar: AppBar(
          title: Text('Search demo'),
        ),
        body: Center(
          child: Builder(
            builder: (context) => MaterialButton(
              child: Text('Search'),
              onPressed: () => showSearch(
                context: context,
                delegate: DummyDelegate(),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class DummyDelegate extends SearchDelegate<String> {
  @override
  List<Widget> buildActions(BuildContext context) => [];

  @override
  Widget buildLeading(BuildContext context) => IconButton(
    icon: Icon(Icons.close),
    onPressed: () => Navigator.of(context).pop(),
  );

  @override
  Widget buildResults(BuildContext context) => Text('Result');

  @override
  Widget buildSuggestions(BuildContext context) => Text('Suggestion');
}

class CustomLocalizationDelegate extends LocalizationsDelegate<MaterialLocalizations> {
  const CustomLocalizationDelegate();

  @override
  bool isSupported(Locale locale) => locale.languageCode == 'en';

  @override
  Future<MaterialLocalizations> load(Locale locale) => SynchronousFuture<MaterialLocalizations>(const CustomLocalization());

  @override
  bool shouldReload(CustomLocalizationDelegate old) => false;

  @override
  String toString() => 'CustomLocalization.delegate(en_US)';
}

class CustomLocalization extends DefaultMaterialLocalizations {
  const CustomLocalization();

  @override
  String get searchFieldLabel => "My hint text";
}

Answer 3

只需将此行插入您要扩展SearchDelegate的Class

class MyClass extends SearchDelegate {
    @override
    String get searchFieldLabel => "Your HINT here";

    ...
} 

输出：

Answer 4

使用此代码：）

class SongSearch extends SearchDelegate<String> {
  SongSearch({
    String hintText = "Song Search",
  }) : super(
          searchFieldLabel: hintText,
          keyboardType: TextInputType.text,
          textInputAction: TextInputAction.search,
        );
.....

Answer 5

使用空值安全，您应该执行以下操作：

class MyDelegate extends SearchDelegate<String> {
  final String? hintText;
  MyDelegate({this.hintText});
  
  @override
  String? get searchFieldLabel => hintText;
  
  // Other overrides...
}

用法：

showSearch<String>(
  context: context,
  delegate: MyDelegate(hintText: 'My hint'),
);

Answer 6

就提示颜色而言，如果您仍在寻找解决方案，则HintColor将不起作用。像这样使用ThemeData的InputDecoration属性：

inputDecorationTheme: InputDecorationTheme(hintStyle: Theme.of(context).textTheme.title.copyWith(color: Colors.white),)

Answer 7

您可以扩展源类并在构造函数中覆盖其默认字段，以为该字段定义自己的值？

例如：

class CustomSearch extends SearchDelegate<String> {
    CustomSearch() : super(searchFieldLabel: "My own hint");
}