实现SearchDelegate

Question

我正在尝试使用SearchDelegate制作自定义应用栏，但出现错误。我正在关注几个教程，但是它们“太老了”。新版本的“ SearchDelegate”具有更多需要覆盖的方法。当我单击条形按钮时发生错误。

appBar: AppBar(
centerTitle: true,
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
actions: <Widget>[
  IconButton(
    icon: Icon(Icons.search),
    onPressed: () {
      showSearch(context: context, delegate: DataSearch(), query: '123');
    },
  )
],
),

import 'package:flutter/material.dart';

class DataSearch implements SearchDelegate<String> {
  final cities = ["Argentina", "Perú", "Uruguay", "Venezuela"];
  final suggestionsList = ["Argentina", "Perú"];
  @override
  String query;

  @override
  ThemeData appBarTheme(BuildContext context) {
    // TODO: implement appBarTheme
    return null;
  }

  @override
  List<Widget> buildActions(BuildContext context) {
    return [IconButton(icon: Icon(Icons.clear), onPressed: () {})];
  }

  @override
  Widget buildLeading(BuildContext context) {
    return IconButton(
        icon: AnimatedIcon(
          icon: AnimatedIcons.menu_arrow,
          progress: transitionAnimation,
        ),
        onPressed: () {});
  }

  @override
  Widget buildResults(BuildContext context) {}

  @override
  Widget buildSuggestions(BuildContext context) {
    // TODO: implement buildSuggestions
    return ListView.builder(
      itemBuilder: (context, index) => ListTile(
        leading: Icon(Icons.location_city),
        title: Text(suggestionsList[index]),
      ),
      itemCount: suggestionsList.length,
    );
  }

  @override
  void close(BuildContext context, String result) {
    // TODO: implement close
  }

  @override
  // TODO: implement keyboardType
  TextInputType get keyboardType => null;

  @override
  // TODO: implement searchFieldLabel
  String get searchFieldLabel => null;

  @override
  void showResults(BuildContext context) {
    // TODO: implement showResults
  }

  @override
  void showSuggestions(BuildContext context) {
    // TODO: implement showSuggestions
  }

  @override
  // TODO: implement textInputAction
  TextInputAction get textInputAction => null;

  @override
  // TODO: implement transitionAnimation
  Animation<double> get transitionAnimation => null;
}

错误屏幕截图

Answer 1

请检查是否需要以下有效的官方演示static Future<String> login(String username, String password) async { var url = _session._getUrl('/auth/login'); var map = new Map<String, dynamic>(); map['username'] = username; map['password'] = password; final response = await http.post(url, body: map); var jsonResponse = convert.jsonDecode(response.body); var cookies = response.headers['set-cookie']; if (cookies != null) { var csrf = _session._getCSRF(cookies); LocalStorage.instance.setString('CSRF', csrf); print(csrf); } return jsonResponse['msg']; }
您可以在

下复制粘贴运行完整代码

工作演示

完整代码

buildResults

Answer 2

您尝试实现SearchDelegate类的接口。但是您的CustomSearchDelegate应该扩展该类。

更改： class DataSearch implements SearchDelegate<String> 至 class DataSearch extends SearchDelegate<String>