如何转换 Map<string, dynamic> 至 Map<int, string> 在 flutter</int,></string,>

Question

这是预期的 map

{
    1: '1000',
    2: '400',
    3: '800',
    4: '7000',
    5: '5000',
    6: '300',
    7: '2000',
    8: '100',
  };

我尝试在firestore中创建它，如下所示

这是我的 model系列，特别是 map

class PackageModel {
  String? id;
  final String? name;
  String? description;
  int? price;
  String? pcolor;
  String? img;
  Map? range;

  PackageModel({
    this.id,
    this.name,
    this.description,
    this.price,
    this.img,
    this.pcolor,
    this.range,
  });

  static PackageModel fromJson(Map<String, dynamic> json) => PackageModel(
        id: json['id'],
        name: json['name'],
        description: json['description'],
        price: json['price'],
        img: json['img'],
        pcolor: json['pcolor'],
        range: json['range'],
      );
}

现在我想在这里使用范围：

updatePackageRange(pack.range as Map<int, String>);

但是我遇到了这个问题

Exception has occurred.
_CastError (type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Map<int, String>' in type cast)

如何使这个<String, dynamic>成为<int, String>

Answer 1

您需要更具体地转换range字段，并且range也应该具有Map<int, String>类型。

class 的更新版本可能如下所示：

class PackageModel {
  String? id;
  final String? name;
  String? description;
  int? price;
  String? pcolor;
  String? img;
  Map<int, String>? range;

  PackageModel({
    this.id,
    this.name,
    this.description,
    this.price,
    this.img,
    this.pcolor,
    this.range,
  });

  static PackageModel fromJson(Map<String, dynamic> json) => PackageModel(
        id: json['id'],
        name: json['name'],
        description: json['description'],
        price: json['price'],
        img: json['img'],
        pcolor: json['pcolor'],
        range: json['range'].map<int, String>(
          (key, value) =>
              MapEntry<int, String>(int.parse(key), value.toString()),
        ),
      );
}