我创建了一个在sqlite数据库中存储一些注释的应用程序。我进行了所有CRUD操作，并且运行良好，但是当我尝试使用SearchDelegate在数据库中进行搜索操作时，出现了一些问题。在使用SearchDelegate进行搜索之前，我将向您展示我的代码
databaseHelper：
import 'dart:async';
import 'package:plants/model/plant.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
class DatabaseHelper {
static final DatabaseHelper _instance = new DatabaseHelper.internal();
factory DatabaseHelper() => _instance;
final String tableNote = 'noteTable';
final String columnId = 'id';
final String columnLocation = 'location';
final String columnTitle = 'title';
final String columnDescription = 'description';
static Database _db;
DatabaseHelper.internal();
Future<Database> get db async {
if (_db != null) {
return _db;
}
_db = await initDb();
return _db;
}
initDb() async {
String databasesPath = await getDatabasesPath();
String path = join(databasesPath, 'notes.db');
// await deleteDatabase(path); // just for testing
var db = await openDatabase(path, version: 1, onCreate: _onCreate);
return db;
}
void _onCreate(Database db, int newVersion) async {
await db.execute(
'CREATE TABLE $tableNote($columnId INTEGER PRIMARY KEY,$columnLocation TEXT, $columnTitle TEXT, $columnDescription TEXT)');
}
Future<int> saveNote(Note note) async {
var dbClient = await db;
var result = await dbClient.insert(tableNote, note.toMap());
// var result = await dbClient.rawInsert(
// 'INSERT INTO $tableNote ($columnTitle, $columnDescription) VALUES (\'${note.title}\', \'${note.description}\')');
return result;
}
Future<List> getAllNotes() async {
var dbClient = await db;
var result = await dbClient.query(tableNote, columns: [columnId, columnLocation , columnTitle, columnDescription]);
// var result = await dbClient.rawQuery('SELECT * FROM $tableNote');
return result.toList();
}
Future<int> getCount() async {
var dbClient = await db;
return Sqflite.firstIntValue(await dbClient.rawQuery('SELECT COUNT(*) FROM $tableNote'));
}
Future<Note> getNote(int id) async {
var dbClient = await db;
List<Map> result = await dbClient.query(tableNote,
columns: [columnId, columnLocation , columnTitle, columnDescription],
where: '$columnId = ?',
whereArgs: [id]);
// var result = await dbClient.rawQuery('SELECT * FROM $tableNote WHERE $columnId = $id');
if (result.length > 0) {
return new Note.fromMap(result.first);
}
return null;
}
Future<int> deleteNote(int id) async {
var dbClient = await db;
return await dbClient.delete(tableNote, where: '$columnId = ?', whereArgs: [id]);
// return await dbClient.rawDelete('DELETE FROM $tableNote WHERE $columnId = $id');
}
Future<int> updateNote(Note note) async {
var dbClient = await db;
return await dbClient.update(tableNote, note.toMap(), where: "$columnId = ?", whereArgs: [note.id]);
// return await dbClient.rawUpdate(
// 'UPDATE $tableNote SET $columnTitle = \'${note.title}\', $columnDescription = \'${note.description}\' WHERE $columnId = ${note.id}');
}
Future close() async {
var dbClient = await db;
return dbClient.close();
}
}
课堂笔记
class Note {
int _id;
String _location;
String _title;
String _description;
Note(this._location,this._title, this._description);
Note.map(dynamic obj) {
this._id = obj['id'];
this._location = obj['location'];
this._title = obj['title'];
this._description = obj['description'];
}
int get id => _id;
String get location => _location;
String get title => _title;
String get description => _description;
Map<String, dynamic> toMap() {
var map = new Map<String, dynamic>();
if (_id != null) {
map['id'] = _id;
}
map['location'] = _location;
map['title'] = _title;
map['description'] = _description;
return map;
}
Note.fromMap(Map<String, dynamic> map) {
this._id = map['id'];
this._location = map ['location'];
this._title = map['title'];
this._description = map['description'];
}
}
List.dart
import 'package:flutter/material.dart';
import 'package:plants/AddPlant.dart';
import 'package:plants/model/plant.dart';
import 'database/dbhelper.dart';
class ListViewNote extends StatefulWidget {
@override
State<StatefulWidget> createState() => new ListViewNoteState();
}
class ListViewNoteState extends State<ListViewNote> {
List<Note> items = new List();
DatabaseHelper db = new DatabaseHelper();
@override
void initState() {
super.initState();
db.getAllNotes().then((notes) {
setState(() {
notes.forEach((note) {
items.add(Note.fromMap(note));
});
});
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Plant List',
),
centerTitle: true,
actions: <Widget>[
IconButton(icon: Icon(Icons.search,
color: Colors.white,), onPressed: (){
showSearch(context: context,
delegate: DataSearch(this.items));
})
],
),
body: Center(
child: ListView.builder(
itemCount: items.length,
padding: const EdgeInsets.all(15.0),
itemBuilder: (context, position) {
return Dismissible(
background: stackBehindDismiss(),
key: ObjectKey(items[position]),
child: Card(
elevation: 2.0,
margin: new EdgeInsets.symmetric(horizontal: 0.0,vertical: 2.0),
child: Column(
children: <Widget>[
ListTile(
title: Text(
'${items[position].title}',
style: TextStyle(
fontSize: 22.0,
color: Colors.deepOrangeAccent,
),
),
subtitle: Text(
'${items[position].description}' + '' + '${items[position].location}',
style: new TextStyle(
fontSize: 18.0,
fontStyle: FontStyle.italic,
),
),
onTap: () => _navigateToNote(context, items[position]),
),
],
),
),
onDismissed: (dirction){
var item = items.elementAt(position);
_deleteNote(context, items[position], position);
Scaffold.of(context).showSnackBar(SnackBar(
content: Text("Item deleted"),
));
},
);
}
),
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.green[700],
child: Icon(Icons.add),
onPressed: () => _createNewNote(context),
),
);
}
void _deleteNote(BuildContext context, Note note, int position) async {
db.deleteNote(note.id).then((notes) {
setState(() {
items.removeAt(position);
});
});
}
void _navigateToNote(BuildContext context, Note note) async {
String result = await Navigator.push(
context,MaterialPageRoute(builder: (context) => NoteScreen(note)),
);
if (result == 'update') {
db.getAllNotes().then((notes) {
setState(() {
items.clear();
notes.forEach((note) {
items.add(Note.fromMap(note));
});
});
});
}
}
void _createNewNote(BuildContext context) async {
String result = await Navigator.push(
context,MaterialPageRoute(builder: (context) => NoteScreen(Note('', '', ''))),
);
if (result == 'save') {
db.getAllNotes().then((notes) {
setState(() {
items.clear();
notes.forEach((note) {
items.add(Note.fromMap(note));
});
});
});
}
}
stackBehindDismiss() {
return Container(
alignment: Alignment.centerRight,
padding: EdgeInsets.only(right: 20.0),
color: Colors.green[700],
child: Icon(
Icons.delete,
color: Colors.white,
),
);
}
}
class DataSearch extends SearchDelegate<Note> {
DatabaseHelper db = new DatabaseHelper();
final List<Note> items = new List();
List<Note> suggestion = new List();
// ListViewNoteState i = ListViewNoteState();
DataSearch(this.suggestion);
@override
ThemeData appBarTheme(BuildContext context) {
assert(context != null);
final ThemeData theme = Theme.of(context);
assert(theme != null);
return theme;
}
@override
List<Widget> buildActions(BuildContext context) {
return [
IconButton(icon: Icon(Icons.clear), onPressed: () {
query = '';
} )
];
}
@override
Widget buildLeading(BuildContext context) {
return IconButton(
icon: AnimatedIcon(
icon: AnimatedIcons.menu_arrow,
progress: transitionAnimation,
),
onPressed: (){
close(context, null);
},
);
}
@override
Widget buildResults(BuildContext context) {
}
@override
Widget buildSuggestions(BuildContext context) {
final suggestion = query.isEmpty
? items
: items.where((target) => target.title.startsWith(query)).toList();
if(items.isEmpty)
{
print("Null");
}
return ListView.builder(
itemBuilder: (context, position)=>
ListTile(
title: Text(items[position].title),
),
itemCount: suggestion.length,
);
}
}
在CRUD上，一切正常，我添加了3条记录，但是当我使用SearchDelegate实施搜索时，没有得到任何结果。
我需要做的是使用搜索栏从数据库中搜索列表
答案 0 :(得分：0)
尝试一下：
return ListView.builder(
itemBuilder: (context, index)=>
ListTile(
title: Text(suggestion[index].title),
),
它应该可以工作并显示正确的结果，至少我的这种工作方式是这样，但是我认为您在构建结果或点击打开结果之类时必须指向项目列表。 / p>