我有一个列表视图，我想把我用红色标记的值加起来，我该怎么做才能把上面的值加起来。

这是上面列表视图中使用的模型，您要添加的值是INT数据类型模型中的“sks”值

class SumValue {
    SumValue({
        this.status,
        this.code,
        this.data,
    });

    String status;
    String code;
    List<Datum> data;

    factory SumValue.fromJson(Map<String, dynamic> json) => SumValue(
        status: json["status"],
        code: json["code"],
        data: List<Datum>.from(json["data"].map((x) => Datum.fromJson(x))),
    );

    Map<String, dynamic> toJson() => {
        "status": status,
        "code": code,
        "data": List<dynamic>.from(data.map((x) => x.toJson())),
    };
}

class Datum {
    Datum({
        this.idTranskripNilai,
        this.idMk,
        this.kodeMk,
        this.nmMk,
        this.sks,
        this.smt,
        this.nilaiAkhirUts,
        this.nilaiHurufUts,
        this.nilaiIndeksUts,
        this.nilaiAkhirUas,
        this.nilaiAkhir,
        this.nilaiHurufAkhir,
        this.nilaiIndeksAkhir,
        this.statusNilaiAkhir,
        this.statusNilaiUts,
        this.updatedBy,
    });

    String idTranskripNilai;
    String idMk;
    dynamic kodeMk;
    String nmMk;
    int sks;
    int smt;
    String nilaiAkhirUts;
    String nilaiHurufUts;
    String nilaiIndeksUts;
    String nilaiAkhirUas;
    String nilaiAkhir;
    String nilaiHurufAkhir;
    String nilaiIndeksAkhir;
    int statusNilaiAkhir;
    int statusNilaiUts;
    String updatedBy;

    factory Datum.fromJson(Map<String, dynamic> json) => Datum(
        idTranskripNilai: json["id_transkrip_nilai"],
        idMk: json["id_mk"],
        kodeMk: json["kode_mk"],
        nmMk: json["nm_mk"],
        sks: json["sks"],
        smt: json["smt"],
        nilaiAkhirUts: json["nilai_akhir_uts"],
        nilaiHurufUts: json["nilai_huruf_uts"],
        nilaiIndeksUts: json["nilai_indeks_uts"],
        nilaiAkhirUas: json["nilai_akhir_uas"] == null ? null : json["nilai_akhir_uas"],
        nilaiAkhir: json["nilai_akhir"] == null ? null : json["nilai_akhir"],
        nilaiHurufAkhir: json["nilai_huruf_akhir"] == null ? null : json["nilai_huruf_akhir"],
        nilaiIndeksAkhir: json["nilai_indeks_akhir"] == null ? null : json["nilai_indeks_akhir"],
        statusNilaiAkhir: json["status_nilai_akhir"] == null ? null : json["status_nilai_akhir"],
        statusNilaiUts: json["status_nilai_uts"] == null ? null : json["status_nilai_uts"],
        updatedBy: json["updated_by"],
    );

    Map<String, dynamic> toJson() => {
        "id_transkrip_nilai": idTranskripNilai,
        "id_mk": idMk,
        "kode_mk": kodeMk,
        "nm_mk": nmMk,
        "sks": sks,
        "smt": smt,
        "nilai_akhir_uts": nilaiAkhirUts,
        "nilai_huruf_uts": nilaiHurufUts,
        "nilai_indeks_uts": nilaiIndeksUts,
        "nilai_akhir_uas": nilaiAkhirUas == null ? null : nilaiAkhirUas,
        "nilai_akhir": nilaiAkhir == null ? null : nilaiAkhir,
        "nilai_huruf_akhir": nilaiHurufAkhir == null ? null : nilaiHurufAkhir,
        "nilai_indeks_akhir": nilaiIndeksAkhir == null ? null : nilaiIndeksAkhir,
        "status_nilai_akhir": statusNilaiAkhir == null ? null : statusNilaiAkhir,
        "status_nilai_uts": statusNilaiUts == null ? null : statusNilaiUts,
        "updated_by": updatedBy,
    };
}

我看到了一些参考文献，但大多数都使用了一个已经有值的列表，例如下面的例子，但如果数据来自API呢

void main() {
  List<Data> listData = [
    Data(count: 10, name: 'a'),
    Data(count: 12, name: 'bc'),
    Data(count: 21, name: 'abc'),
  ];

  int sum = listData.fold(0, (int preValue, data) => preValue + data.count);

  print(sum);// 43
}

class Data {
  int count;
  String name;
  Data({required this.count, required this.name});
}