如何实现一个 Flutter 搜索应用栏

Question

有很多教程，但没有帮助我前进，我迷失在所有可能的选项中，或者我不知道如何改进代码（我想使用一个显示列表的应用程序不仅仅是三个水果或三个城市的名称？）

我找到了创建一个很好的 SearchBar 的教程，它能够根据输入的第一个字母显示结果。

我不明白如何使用包含与内容相关联的标题的数据列表来编辑教程。 如果第一个字母是小写或大写，我不明白如何显示结果。 能不能帮我做一个简单的基本代码，可以服务于所有人，包括像我这样的初学者？

DataList.dart

List<ListWords>  listWords = [
  ListWords('oneWord', 'OneWord definition'),
  ListWords('twoWord', 'TwoWord definition.'),
  ListWords('TreeWord', 'TreeWord definition'),
];

class ListWords {
  String titlelist;
  String definitionlist;

  ListWords(String titlelist, String definitionlist) {
    this.titlelist = titlelist;
    this.definitionlist = definitionlist;
  }
}

搜索栏.dart

import 'package:flutter/material.dart';
import 'package:test_searchbar/DataList.dart';

class SearchBar extends StatelessWidget {


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Search App'),
        actions: <Widget>[
          IconButton(icon: Icon(Icons.search),
              onPressed: () {
                showSearch(context: context, delegate: DataSearch(listWords));
              })
        ],
      ),
      drawer: Drawer(),
    );
  }
}

class DataSearch extends SearchDelegate<String> {

  final List<ListWords> listWords;

  DataSearch(this.listWords);


  @override
  List<Widget> buildActions(BuildContext context) {
    //Actions for app bar
    return [IconButton(icon: Icon(Icons.clear), onPressed: () {
      query = '';
    })];
  }

  @override
  Widget buildLeading(BuildContext context) {
    //leading icon on the left of the app bar
    return IconButton(
        icon: AnimatedIcon(icon: AnimatedIcons.menu_arrow,
          progress: transitionAnimation,
        ),
        onPressed: () {
          close(context, null);
        });
  }

  @override
  Widget buildResults(BuildContext context) {
    // show some result based on the selection
    return Center(
      child: Text(query),

    );
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    // show when someone searches for something
    final suggestionList = query.isEmpty
        ? listWords
        : listWords.where((p) => p.startsWith(query)).toList();



    return ListView.builder(itemBuilder: (context, index) => ListTile(
      onTap: () {
        showResults(context);
      },
      trailing: Icon(Icons.remove_red_eye),
      title: RichText(
        text: TextSpan(
            text: suggestionList[index].titlelist.substring(0, query.length),
            style: TextStyle(
                color: Colors.red, fontWeight: FontWeight.bold),
            children: [
              TextSpan(
                  text: suggestionList[index].titlelist.substring(query.length),
                  style: TextStyle(color: Colors.grey))
            ]),
      ),
    ),
      itemCount: suggestionList.length,
    );
  }
}

Answer 1

要创建一个搜索应用栏，您需要一个带有以下代码的有状态小部件，

在你的 State 类中，

  TextEditingController _searchQueryController = TextEditingController();
  bool _isSearching = false;
  String searchQuery = "Search query";

在 Scaffold 中，您的 appbar 应该是这样的，

appBar: AppBar(
        leading: _isSearching ? const BackButton() : Container(),
        title: _isSearching ? _buildSearchField() : _buildTitle(context),
        actions: _buildActions(),
      ),

定义显示和管理搜索栏所需的以下方法，

Widget _buildSearchField() {
    return TextField(
      controller: _searchQueryController,
      autofocus: true,
      decoration: InputDecoration(
        hintText: "Search Data...",
        border: InputBorder.none,
        hintStyle: TextStyle(color: Colors.white30),
      ),
      style: TextStyle(color: Colors.white, fontSize: 16.0),
      onChanged: (query) => updateSearchQuery(query),
    );
  }

  List<Widget> _buildActions() {
    if (_isSearching) {
      return <Widget>[
        IconButton(
          icon: const Icon(Icons.clear),
          onPressed: () {
            if (_searchQueryController == null ||
                _searchQueryController.text.isEmpty) {
              Navigator.pop(context);
              return;
            }
            _clearSearchQuery();
          },
        ),
      ];
    }

    return <Widget>[
      IconButton(
        icon: const Icon(Icons.search),
        onPressed: _startSearch,
      ),
    ];
  }

  void _startSearch() {
    ModalRoute.of(context)
        .addLocalHistoryEntry(LocalHistoryEntry(onRemove: _stopSearching));

    setState(() {
      _isSearching = true;
    });
  }

  void updateSearchQuery(String newQuery) {
    setState(() {
      searchQuery = newQuery;
    });
  }

  void _stopSearching() {
    _clearSearchQuery();

    setState(() {
      _isSearching = false;
    });
  }

  void _clearSearchQuery() {
    setState(() {
      _searchQueryController.clear();
      updateSearchQuery("");
    });
  }

这是在任何 Flutter 屏幕中实现应用搜索栏的最佳方式。

Answer 2

最后，我设法做到了。这是在列表中搜索显示的一个很好的起点。这是正确的吗？

DataList.dart

List<ListWords>  listWords = [
  ListWords('oneWord', 'OneWord definition'),
  ListWords('twoWord', 'TwoWord definition.'),
  ListWords('TreeWord', 'TreeWord definition'),
];

class ListWords {
  String titlelist;
  String definitionlist;

  ListWords(String titlelist, String definitionlist) {
    this.titlelist = titlelist;
    this.definitionlist = definitionlist;
  }
}

SearchBar.dart

import 'dart:core';
import 'package:flutter/material.dart';
import 'package:test_searchbar/DataList.dart';
import 'package:test_searchbar/detail.dart';

class SearchBar extends StatelessWidget {


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Search App'),
        actions: <Widget>[
          IconButton(icon: Icon(Icons.search),
              onPressed: () {
                showSearch(context: context, delegate: DataSearch(listWords));
              })
        ],
      ),
      body: Center(
          child: Text('default content')
      ),
      drawer: Drawer(),
    );
  }
}

class DataSearch extends SearchDelegate<String> {

  final List<ListWords> listWords;

  DataSearch(this.listWords);

  @override
  List<Widget> buildActions(BuildContext context) {
    //Actions for app bar
    return [IconButton(icon: Icon(Icons.clear), onPressed: () {
      query = '';
    })];
  }

  @override
  Widget buildLeading(BuildContext context) {
    //leading icon on the left of the app bar
    return IconButton(
        icon: AnimatedIcon(icon: AnimatedIcons.menu_arrow,
          progress: transitionAnimation,
        ),
        onPressed: () {
          close(context, null);
        });
  }

  @override
  Widget buildResults(BuildContext context) {
    // show some result based on the selection
    final suggestionList = listWords;

    return ListView.builder(itemBuilder: (context, index) => ListTile(

      title: Text(listWords[index].titlelist),
      subtitle: Text(listWords[index].definitionlist),
    ),
      itemCount: suggestionList.length,
    );
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    // show when someone searches for something

    final suggestionList = query.isEmpty
        ? listWords
        : listWords.where((p) => p.titlelist.contains(RegExp(query, caseSensitive: false))).toList();


    return ListView.builder(itemBuilder: (context, index) => ListTile(
      onTap: () {
        Navigator.push(
          context,
          MaterialPageRoute(
            builder: (context) => Detail(listWordsDetail: suggestionList[index]),
          ),
        );
      },
      trailing: Icon(Icons.remove_red_eye),
      title: RichText(
        text: TextSpan(
            text: suggestionList[index].titlelist.substring(0, query.length),
            style: TextStyle(
                color: Colors.red, fontWeight: FontWeight.bold),
            children: [
              TextSpan(
                  text: suggestionList[index].titlelist.substring(query.length),
                  style: TextStyle(color: Colors.grey)),
            ]),
      ),
    ),
      itemCount: suggestionList.length,
    );
  }
}

detail.dart

import 'package:flutter/material.dart';
import 'package:test_searchbar/DataList.dart';

class Detail extends StatelessWidget {

  final ListWords listWordsDetail;

  Detail({Key key, @required this.listWordsDetail}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          brightness: Brightness.dark,
          title: const Text('Détail', style: TextStyle(color: Colors.white)),
          iconTheme: IconThemeData(color: Colors.white),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text(listWordsDetail.titlelist +' (on detail page)'),
              Text(listWordsDetail.definitionlist),
            ],
          ),
        )
    );
  }
}

如果从详情页返回，最好打开带有默认内容的搜索栏页面，并关闭搜索栏...

Answer 3

Scaffold(
        appBar: AppBar(
          backgroundColor: Color.fromRGBO(93, 25, 72, 1),
          toolbarHeight: 60.0,
          title: TextField(
            cursorColor: Colors.white,
            decoration: InputDecoration(
                hintText: " Search...",
                border: InputBorder.none,
                suffixIcon: IconButton(
                  icon: Icon(Icons.search),
                  color: Color.fromRGBO(93, 25, 72, 1),
                  onPressed: () {},
                )),
            style: TextStyle(color: Colors.white, fontSize: 15.0),
          ),
        ),
);