嘗試在Flutter的POSThttp請求中傳遞JSON陣列

我正在嘗試向我的 POST Http 請求發送一個 json 陣列作為正文，但它會引發此錯誤：

Unhandled Exception: Converting object to an encodable object failed: Instance of 'Athlete'

我想將一個只有運動員模型的三個引數的陣列傳遞給發布請求。你能幫我弄清楚我該怎么做嗎？

我的模型

List<Athlete> athleteFromJson(String str) =>
    List<Athlete>.from(json.decode(str).map((x) => Athlete.fromJson(x)));
String athleteToJson(List<Athlete> data) =>
    json.encode(List<dynamic>.from(data.map((x) => x.toJson())));

class Athlete {
  Athlete(
      {required this.id,
      required this.firstName,
      required this.lastName,
      required this.fatherName,
      required this.currentMonthPresences,
      this.isSelected = false,
      required this.hasDebt,
      this.department,
      this.teamKey});

  late int id;
  late String firstName;
  late String lastName;
  late String fatherName;
  late int currentMonthPresences;
  bool isSelected = false;
  late bool hasDebt;
  final Department? department;
  final TeamKey? teamKey;

  factory Athlete.fromJson(Map<String, dynamic> json) => Athlete(
        id: json['id'],
        firstName: json['firstName'],
        lastName: json['lastName'],
        fatherName: json['fatherName'],
        currentMonthPresences: json['currentMonthPresences'],
        hasDebt: json['hasDebt'],
        department: Department.fromJson(json["department"]),
        teamKey: TeamKey.fromJson(json["team"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "firstName": firstName,
        "lastName": lastName,
        "fatherName": fatherName,
        "currentMonthPresences": currentMonthPresences,
        "hasDebt": hasDebt,
        "department": department?.toJson(),
        "teamKey": teamKey?.toJson(),
      };

  Athlete.newSelectedAthlete(this.id, this.department, this.teamKey);
}

我將陣列發送到 POST 請求的螢屏

class SelectedAthletes extends StatefulWidget {
  const SelectedAthletes({Key? key}) : super(key: key);

  static const routeName = '/selectedAthletes';

  @override
  State<SelectedAthletes> createState() => _SelectedAthletesState();
}

class _SelectedAthletesState extends State<SelectedAthletes> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    final args = ModalRoute.of(context)!.settings.arguments as List<Athlete>;
    return Scaffold(
        body: Stack(
          children: [
            SingleChildScrollView(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  ListView.builder(
                    shrinkWrap: true,
                    cacheExtent: 34,
                    primary: true,
                    physics: const ClampingScrollPhysics(),
                    padding: const EdgeInsets.only(
                      top: 10,
                      bottom: 56,
                    ),
                    itemCount: args.length,
                    itemBuilder: (BuildContext context, int index) {
                      return ListTile(
                          title: Column(
                            mainAxisSize: MainAxisSize.min,
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              Row(
                                children: [
                                  Text(
                                    'ID: ${args[index].id}',
                                    style: const TextStyle(
                                        color: Colors.blue, fontSize: 14),
                                  ),
                                ],
                              ),
                              Row(
                                children: [
                                  Flexible(
                                    child: Text(
                                      '${args[index].lastName} ${args[index].firstName}',
                                      style: const TextStyle(
                                          color: Colors.black,
                                          fontFamily: 'Cera',
                                          fontWeight: FontWeight.bold,
                                          fontSize: 18),
                                    ),
                                  ),
                                ],
                              ),
                            ],
                          ));
                    },
                  )
                ],
              ),
            ),
            Align(
              alignment: Alignment.bottomCenter,
              child: Container(
                width: double.infinity,
                height: 60,
                child: ElevatedButton(
                  style: ElevatedButton.styleFrom(
                      disabledBackgroundColor: Colors.grey),
                  onPressed: () async {
                    ApiService.insertPresences(getJsonArray(args));
                  },
                  child: const Center(
                    child: Text(
                      'SEND',
                      style: TextStyle(
                          fontWeight: FontWeight.bold,
                          color: Colors.white,
                          fontSize: 18),
                    ),
                  ),
                ),
              ),
            ),
          ],
        ));
  }

  String getJsonArray(List<Athlete> args) {
    var selectedAthletes = <Athlete>[];

    for (int i = 0; i < args.length; i  ) {
      Athlete sa = Athlete.newSelectedAthlete(
          args[i].id, args[i].department, args[i].teamKey);
      selectedAthletes.add(sa);
    }

    var jsonExport = json.encode(selectedAthletes);
    print(jsonExport);
    return jsonExport;
  }
}

我的 POST 請求

static Future<Athlete?> insertPresences(String getJson) async {
    try {
      final response = await http.post(
        Uri.parse('$uri/insert-presences'),
        headers: <String, String>{
          'Authorization': 'Basic ...',
          'Content-Type': 'application/json; charset=UTF-8',
          'Accept': 'application/json'
        },
        body: json.encode([
          {
            "getJson": getJson
          }
        ]),
      );
      print('Response status: ${response.statusCode}');
      print('Response body: ${response.body}');

      if (response.statusCode == 200) {
        print("status 200");
        return null;
    } catch (e) {
      logger.e(e.toString());
    }
    return null;
  }

我在郵遞員中的原始身體

[
    {
        "athleteId" : "16198",
        "departmentId":"3",
        "teamId":"278"
    }
]

uj5u.com熱心網友回復：

可能是因為你的模型 toJson 方法，它應該是這樣的

 class Athlete {
  String? athleteId;
  String? departmentId;
  String? teamId;

  Athlete({this.athleteId, this.departmentId, this.teamId});

  Athlete.fromJson(Map<String, dynamic> json) {
    athleteId = json['athleteId'];
    departmentId = json['departmentId'];
    teamId = json['teamId'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['athleteId'] = this.athleteId;
    data['departmentId'] = this.departmentId;
    data['teamId'] = this.teamId;
    return data;
  }
}

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