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您好，我想解析 Json，我遇到了这个问题，有什么问题请帮助
错误是 'List' 不是类型 'Map<String, dynamic>'
模型的子类型

class CategoriesModel {
  CategoriesModel({
    this.id,
    this.title,
    this.price,
    this.description,
    this.image,
  });

  int? id;
  String? title;
  double? price;
  String? description;
  String? image;

  factory CategoriesModel.fromJson(Map<String, dynamic> json) {
    return CategoriesModel(
      id: json["id"],
      title: json["title"],
      price: json["price"].toDouble(),
      description: json["description"],
      image: json["image"],
    );
  }


  Map<String, dynamic> toMap() => {
    "id": id,
    "title": title,
    "price": price,
    "description": description,
    "image": image,
  };
}

我做了这个（AppCubit.dart ）

CategoriesModel? categoriesModel ;

   getCategories(){
    emit(OnLoadingCategoriesState());
    DioHelper.getData(pathUrl: "products").then((value){
      categoriesModel = CategoriesModel.fromJson(value.data);
      // catList =  (value.data as List)
      //     .map((x) => CategoriesModel.fromJson(x))
      //     .toList();
      // print(catList.length);

      emit(OnSuccessCategoriesState());
    }).catchError((error){
      emit(OnCatchErrorCategoriesState(error.toString()));
      print(error.toString());
    });
  }

在Dio Helper 我做了通用功能来使用它

  static Future<Response> getData({required pathUrl})async{
   return await dio.get(pathUrl);
  }

这是来自json的小数据

[
  {
    "id": 1,
    "title": "Fjallraven - Foldsack No. 1 Backpack, Fits 15 Laptops",
    "price": 109.95,
    "description": "Your perfect pack for everyday use and walks in the forest. Stash your laptop (up to 15 inches) in the padded sleeve, your everyday",
    "category": "men's clothing",
    "image": "https://fakestoreapi.com/img/81fPKd-2AYL._AC_SL1500_.jpg"
  },
  {
    "id": 2,
    "title": "Mens Casual Premium Slim Fit T-Shirts ",
    "price": 22.3,
    "description": "Slim-fitting style, contrast raglan long sleeve, three-button henley placket, light weight & soft fabric for breathable and comfortable wearing. And Solid stitched shirts with round neck made for durability and a great fit for casual fashion wear and diehard baseball fans. The Henley style round neckline includes a three-button placket.",
    "category": "men's clothing",
    "image": "https://fakestoreapi.com/img/71-3HjGNDUL._AC_SY879._SX._UX._SY._UY_.jpg"
  },
]

最后这是我出现的错误

I/flutter (31455): onChange -- AppCubit, Change { currentState: Instance of 'OnLoadingCategoriesState', nextState: Instance of 'OnCatchErrorCategoriesState' }
I/flutter (31455): type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'

任何帮助我都会感激

4

1 回答 1

1

CategoriesModel.fromJson期待类型Map<String, dynamic>，但 json 片段显示响应是List.

更新.then处理列表的函数并CategoriesModel从 中的每个项目创建List，类似于上面代码片段中注释掉的代码。

 DioHelper.getData(pathUrl: "products").then((List values) {
     values.map((e) => CategoriesModel.fromJson(e)).toList();
 }
于 2021-06-16T21:27:21.887 回答