Question

我正在尝试将build_value和json_serializable一起用于解析从服务器到模型类的json响应。

以下是依赖项：

  built_collection: ^4.0.0
  built_value: ^6.1.4
dev_dependencies:
  build_runner: ^1.0.0
  built_value_generator: ^6.1.4
  json_serializable: ^1.4.0

以下是我编写的代码

abstract class UserData implements Built<UserData, UserDataBuilder>{

  String get user_first_name;
  String get user_last_name;
  String get user_mobile;
  String get email;
  String get user_type;
  Company get company;
  UserType get type;

  UserData._();
  factory UserData([updates(UserDataBuilder b)]) = _$UserData;
  static Serializer<UserData> get serializer => _$userDataSerializer;

}

abstract class Company implements Built<Company, CompanyBuilder>{

  String get id;

  Company._();
  factory Company([updates(CompanyBuilder b)]) = _$Company;
  static Serializer<Company> get serializer => _$companySerializer;


}


abstract class UserType implements Built<UserType, UserTypeBuilder>{

  String get id;
  UserType._();
  factory UserType([updates(UserTypeBuilder b)]) = _$UserType;
  static Serializer<UserType> get serializer => _$userTypeSerializer;


}

序列化器类代码：

@SerializersFor(const [
  UserData
])

Serializers serializers = _$serializers;

Serializers standardSerializers =
(serializers.toBuilder()..addPlugin(StandardJsonPlugin())).build();

以下是我从服务器获得的响应。

{
  "user": {
    "id": "505d27b0-acaa-11e8-b916-21359608417b",
    "email": "example@gmail.com",
    "user_first_name": "Pankaj",
    "user_last_name": "P",
    "user_dob": null,
    "active_status": 1,
    "user_region_id": null,
    "user_base_currency": "USD",
    "user_address": null,
    "is_god_user": 0,
    "is_super_user": 0,
    "profile": null,
    "advanced_search": 0,
    "region": null,
    "company": {
      "id": "24e311f0-acaa-11e8-8750-8de299c7797b",
      "company_name": "SHPR A",
      "company_address": null,
      "company_logo": "",
      "company_constitution": "pvt_ltd",
      "company_email": "shpra@mail.com",
      "state": null,
      "country": null,
      "postal_code": null,
      "date_of_establishment": null,
      "number_of_employees": null,
      "company_turnover": null,
      "vendor_id": null
    },
    "type": {
      "id": "5eeebe55-fdf4-11e7-81f1-ac7ba173bed6",
      "user_type_code": "11",
      "user_type_name": "ADMIN",
      "user_category": "SHIPPER"
    }
  }
}

最后，我尝试使用以下代码行进行解析

serializers.deserializeWith(UserData.serializer, json.decode(response.body))

但是我遇到以下错误

failed due to: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Iterable<dynamic>' in type cast

请阐明可能导致此问题的原因。

Answer 1

堆栈跟踪可以告诉您错误在哪里，所以如果有错误，它可能会很有用。

有时，您正在将Map<String, dynamic>值分配给类型为Iterable<dynamic>的变量。这听起来像JSON解码出错，有些事情是假设列表并获取地图。

提供的代码中没有假设Iterable<dynamic>的内容，因此在json_serializable包中最有可能爆炸的事情。

因此，您确定您拥有的JSON输入文本是json_serializable解码器的正确格式吗？（我不熟悉该程序包，因此只能猜测）。

Answer 2

我也遇到了同样的问题，替换

serializers.deserializeWith(UserData.serializer, json.decode(response.body))

使用

standardSerializers.deserializeWith(UserData.serializer, json.decode(response.body))

'_InternalLinkedHashMap <string，dynamic =“”>'在类型转换中不是'Iterable <dynamic>'类型的子类型

2 个答案: