我完全是sqliteand的初學者flutter。我試圖為database我的顫振創建一個本地應用程式。所以我看了一些 youtube 視頻并開始使用 Fluttersqflite插件實作一個資料庫。一切正常，因為我所做的只是復制輸入你的塊莖代碼，直到我不得不在代碼中添加一個額外的引數，這是一個布林值，以跟蹤任務的狀態（比如是否完成了任務）。我使用了一個int值來保存bool, whilesqlite不支持boolean值。我使用了兩個functions，一個用于更新，text另一個用于更新switch值。
其次，當我點擊一個開關時，它會觸發list. 我也想解決這個問題。
任務的模型類
class Tasksdb {
final int? id;
final String taskName;
bool isDone;
Tasksdb({
this.id,
required this.taskName,
required this.isDone,
});
factory Tasksdb.fromMap(Map<String, dynamic> json) => Tasksdb(
id: json['id'],
taskName: json['taskName'],
isDone: (json['isDone'] as int) == 0 ? false : true);
Map<String, dynamic> toMap() {
return {
'id': id,
'taskName': taskName,
'isDone': isDone,
};
}
}
資料庫助手類
class DatabaseHelper {
DatabaseHelper._privateConstructor();
static final DatabaseHelper instance = DatabaseHelper._privateConstructor();
static Database? _database;
Future<Database> get database async => _database ??= await _initDatabase();
Future<Database> _initDatabase() async {
Directory documentsDirectory = await getApplicationDocumentsDirectory();
String path = join(documentsDirectory.path, 'tasks.db');
return await openDatabase(
path,
version: 1,
onCreate: _onCreate,
);
}
Future _onCreate(Database db, int version) async {
await db.execute('''
CREATE TABLE IF NOT EXISTS "taskstable" (
"id" INTEGER,
"taskName" TEXT,
"isDone" INTEGER NOT NULL DEFAULT 0,
PRIMARY KEY("id" AUTOINCREMENT)
);
''');
}
Future<List<Tasksdb>> getTasks() async {
Database db = await instance.database;
var tasksQuery = await db.query(
'taskstable',
);
List<Tasksdb> taskList = tasksQuery.isNotEmpty
? tasksQuery.map((c) => Tasksdb.fromMap(c)).toList()
: [];
return taskList;
}
Future<int> add(Tasksdb task) async {
Database db = await instance.database;
return await db.insert('taskstable', {
'id': task.id,
'taskName': task.taskName,
'isDone': 0,
});
}
Future<int> update(Tasksdb task) async {
Database db = await instance.database;
return await db.update(
'taskstable',
task.toMap(),
where: "id = ?",
whereArgs: [task.id],
);
}
Future<int> updateIsDone(bool isDoneTodb) async {
Database db = await instance.database;
return await db.update(
'taskstable',
{
'isDone': isDoneTodb == true ? 1 : 0,
},
);
}
}
主螢屏小部件
class SqliteApp extends StatefulWidget {
const SqliteApp({Key? key}) : super(key: key);
@override
_SqliteAppState createState() => _SqliteAppState();
}
class _SqliteAppState extends State<SqliteApp> {
int? selectedId;
final textController = TextEditingController();
bool isDone = false;
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: TextField(
controller: textController,
),
),
body: Center(
child: FutureBuilder<List<Tasksdb>>(
future: DatabaseHelper.instance.getTasks(),
builder: (BuildContext context,
AsyncSnapshot<List<Tasksdb>> snapshot) {
if (!snapshot.hasData) {
return const Center(child: Text('Loading...'));
}
return snapshot.data!.isEmpty
? const Center(child: Text('No tasks in List.'))
: ListView(
children: snapshot.data!.map((task) {
return Center(
child: Card(
color: selectedId == task.id
? Colors.green
: Colors.yellow,
child: ListTile(
trailing: Switch( //the problem is here, doesn't save to db
value: isDone,
onChanged: (val) async {
setState(() {
isDone = val;
});
await DatabaseHelper.instance
.updateIsDone(
isDone,
);
}),
title: Text(task.taskName),
onTap: () {
setState(() {
if (selectedId == null) {
textController.text = task.taskName;
selectedId = task.id;
} else {
textController.text = 'add something';
selectedId = null;
}
});
},
),
),
);
}).toList(),
);
}),
),
floatingActionButton: FloatingActionButton(
onPressed: () async {
await DatabaseHelper.instance.add(
Tasksdb(
taskName: textController.text,
isDone: false,
),
);
setState(() {
textController.clear();
selectedId = null;
});
},
),
),
);
}
}
uj5u.com熱心網友回復：
我找到了答案：（如果有人有同樣的問題）我isDone從材料應用程式小部件中洗掉了 bool，而不是將開關分配val給bool我將它分配給資料庫的task.isDone值。為了避免開關的自動觸發，我Taskdb將updateIsDone function
Future<int> updateIsDone(Tasksdb task, bool isDoneTodb) async {
Database db = await instance.database;
return await db.update(
'taskstable',
{
'isDone': isDoneTodb == true ? 1 : 0,
},
where: "id = ?",
whereArgs: [task.id]);
}
...
Switch(
value: task.isDone,
onChanged: (val) async {
setState(() {
task.isDone = val;
});
await DatabaseHelper.instance
.updateIsDone(task, task.isDone);
});
轉載請註明出處，本文鏈接：https://www.uj5u.com/gongcheng/471132.html