我正在嘗試將資料保存在 SQFlite 資料庫中！值“公里”發生錯誤。在我收到此錯誤之前，它應該是 int 。然后我嘗試將值更改為字串。之后我得到相反的錯誤，說'int不是String的子型別'。其實我不知道出了什么問題。
這是我的代碼：
class MyCar:
'''
final String tableCar='car';
class CarFields{
static final List<String> values=[
id,marke,modell,baujahr, motor,hubraum, kilometer
];
static final String id='_id';
static final String marke='marke';
static final String modell='modell';
static final String baujahr='baujahr';
static final String motor='motor';
static final String hubraum='hubraum';
static final String kilometer='kilometer';
}
class MyCar{
final int? id;
final String marke;
final String modell;
final String baujahr;
final String motor;
final String hubraum;
final int kilometer;
const MyCar({
this.id,
required this.marke,
required this.modell,
required this.baujahr,
required this.motor,
required this.hubraum,
required this.kilometer,
});
MyCar copy({
int? id,
String? marke,
String? modell,
String? baujahr,
String? motor,
String? hubraum,
int? kilometer,
}) => MyCar(
id: id?? this.id,
marke: marke?? this.marke,
modell: modell ?? this.modell,
baujahr: baujahr ?? this.baujahr,
motor: motor?? this.motor,
hubraum: hubraum ?? this.hubraum,
kilometer: kilometer ?? this.kilometer,
);
static MyCar fromJson(Map<String, Object?> json)=> MyCar(
id: json[CarFields.id] as int?,
marke: json[CarFields.marke] as String,
modell: json[CarFields.modell] as String,
baujahr: json[CarFields.baujahr] as String,
motor: json[CarFields.motor] as String,
hubraum: json[CarFields.hubraum] as String,
kilometer: json[CarFields.kilometer] as int,
);
Map<String, Object?> toJson()=>{
CarFields.id:id,
CarFields.marke:marke,
CarFields.modell:modell,
CarFields.baujahr:baujahr,
CarFields.motor:motor,
CarFields.hubraum:hubraum,
CarFields.kilometer:kilometer,
};
}
'''
class CarFormWidget:
'''
import 'package:flutter/material.dart';
class CarFormWidget extends StatelessWidget{
final String? marke;
final String? modell;
final String? baujahr;
final String? motor;
final String? hubraum;
final int? kilometer;
final ValueChanged<String> onChangedMarke;
final ValueChanged<String> onChangedModell;
const CarFormWidget({
Key? key,
this.marke='',
this.modell='',
this.baujahr='',
this.motor='',
this.hubraum='',
this.kilometer=0,
required this.onChangedMarke,
required this.onChangedModell,
}): super(key:key);
@override
Widget build(BuildContext context) => SingleChildScrollView(
child: Padding(
padding: EdgeInsets.all(16),
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Row(
),
buildMarke(),
SizedBox(height: 8),
buildModell(),
SizedBox(height: 8),
buildBaujahr(),
SizedBox(height: 8),
buildMotor(),
SizedBox(height: 8),
buildHubraum(),
SizedBox(height: 8),
buildKilometer(),
],
),
),
);
Widget buildMarke() => TextFormField(
maxLines: 1,
initialValue: marke,
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Marke',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (marke) =>
marke != null && marke.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
Widget buildModell() => TextFormField(
maxLines: 1,
initialValue: modell,
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Modell',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (modell) =>
modell != null && modell.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
Widget buildBaujahr() => TextFormField(
maxLines: 1,
initialValue: baujahr,
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Baujahr',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (baujahr) =>
baujahr != null && baujahr.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
Widget buildMotor() => TextFormField(
maxLines: 1,
initialValue: motor,
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Motor',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (motor) =>
motor != null && motor.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
Widget buildHubraum() => TextFormField(
maxLines: 1,
initialValue: hubraum,
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Hubraum',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (hubraum) =>
hubraum != null && hubraum.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
Widget buildKilometer() => TextFormField(
maxLines: 1,
initialValue: 'Kilometer',
style: TextStyle(
color: Colors.white70,
fontWeight: FontWeight.bold,
fontSize: 24,
),
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'Kilometer',
hintStyle: TextStyle(color: Colors.white70),
),
validator: (kilometer) =>
kilometer != null && kilometer.isEmpty ? 'The Marke cannot be empty' : null,
onChanged: onChangedMarke,
);
}
'''
class CarDatabase:
'''
import 'package:path/path.dart';
import 'package:recarable/classes/MyCar.dart';
import 'package:sqflite/sqflite.dart';
class CarDatabase {
static final CarDatabase instance = CarDatabase._init();
static Database? _database;
CarDatabase._init();
Future<Database> get database async {
if (_database != null) return _database!;
_database = await _initDB('MyCars.db');
return _database!;
}
Future<Database> _initDB(String filePath) async {
final dbPath = await getDatabasesPath();
final path = join(dbPath, filePath);
return await openDatabase(path, version: 1, onCreate: _createDB);
}
Future _createDB(Database db, int version) async {
final idType = 'INTEGER PRIMARY KEY AUTOINCREMENT';
final textType = 'TEXT NOT NULL';
final integerType = 'INTEGER NOT NULL';
await db.execute('''
CREATE TABLE $tableCar (
${CarFields.id} $idType,
${CarFields.marke} $textType,
${CarFields.modell} $textType,
${CarFields.baujahr} $textType,
${CarFields.motor} $textType,
${CarFields.hubraum} $textType,
${CarFields.kilometer} $textType
)
''');
}
//
Future<MyCar> create(MyCar mycar) async {
final db = await instance.database;
final id = await db.insert(tableCar, mycar.toJson());
return mycar.copy(id: id);
}
Future<MyCar> readNote(int id) async {
final db = await instance.database;
final maps = await db.query(
tableCar,
columns: CarFields.values,
where: '${CarFields.id}=?',
whereArgs: [id],
);
if (maps.isNotEmpty) {
return MyCar.fromJson(maps.first);
} else {
throw Exception('ID $id not found');
}
}
Future<List<MyCar>> readAllMyCars() async {
final db = await instance.database;
final orderBy = '${CarFields.id} ASC';
final result = await db.query(tableCar, orderBy: orderBy);
return result.map((json) => MyCar.fromJson(json)).toList();
}
Future<int> update(MyCar mycar) async {
final db = await instance.database;
return db.update(
tableCar,
mycar.toJson(),
where: '${CarFields.id}=?',
whereArgs: [mycar.id],
);
}
Future<int> delete(int id) async {
final db = await instance.database;
return await db.delete(
tableCar,
where: '${CarFields.id}=?',
whereArgs: [id],
);
}
Future close() async {
final db = await instance.database;
db.close();
}
}
'''
uj5u.com熱心網友回復：
也許您得到的回應不一致。有些資料是整數，有些是字串。因此，避免出現此錯誤的最佳方法是使用動態。
只需在您的 MyCar 類中使用動態公里數。另外，洗掉為 int
MyCar copy({
int? id,
String? marke,
String? modell,
String? baujahr,
String? motor,
String? hubraum,
dynamic kilometer,
}) => MyCar(
id: id?? this.id,
marke: marke?? this.marke,
modell: modell ?? this.modell,
baujahr: baujahr ?? this.baujahr,
motor: motor?? this.motor,
hubraum: hubraum ?? this.hubraum,
kilometer: kilometer ?? this.kilometer,
);
static MyCar fromJson(Map<String, Object?> json)=> MyCar(
id: json[CarFields.id] as int?,
marke: json[CarFields.marke] as String,
modell: json[CarFields.modell] as String,
baujahr: json[CarFields.baujahr] as String,
motor: json[CarFields.motor] as String,
hubraum: json[CarFields.hubraum] as String,
kilometer: json[CarFields.kilometer],
);
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