Flutter - Change search hint text of SearchDelegate

问题

In current implementation of SearchDelegate, there is no option to change the hint text. When the query is empty, search screen is displaying "Search" in the query field as a hint text.

Hint text is currently defined on line 395 as follows:

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

There is, however, an existing issue to this subject reported.

I wasn't able to come up with any solution for this. Do you know any workaround for the issue?

回答1:

There is a workaround for this by creating your own DefaultMaterialLocalizations class and passing it into the MaterialApp widget:

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";
}

回答2:

Currently SearchDelegate has an optional member "searchFieldLabel" to specify the label of the search field. It should look something like this:

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

回答3:

Use this code :)

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

回答4:

As far as the hint color is concerned, if you're still looking for a solution, HintColor won't work. Use the InputDecoration property of ThemeData like so:

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

回答5:

You can just extend the source class and override its default field in your constructor to define your own value for the field?

For example:

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

来源：https://stackoverflow.com/questions/54518741/flutter-change-search-hint-text-of-searchdelegate

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