错误：String类型不是Map String类型的子类型，动态

问题描述 投票：0回答：2

出现错误：字符串类型不是动态映射字符串类型的子类型

import 'package:ajooyo/features/products/models/product_model.dart';

class CartItem {
  final Product product;
  final int quantity;
  final String id;

  CartItem({
    required this.product,
    required this.quantity,
    required this.id,
  });

  factory CartItem.fromJson(Map<String, dynamic> json) {
    return CartItem(
      product: Product.fromJson(json['product']),
      quantity: json['quantity'],
      id: json['_id'],
    );
  }
}

Cart model

import 'package:ajooyo/features/products/models/product_cart_item_model.dart';

class Cart {
  final String id;
  final String userId;
  final List<CartItem> items;

  Cart({
    required this.id,
    required this.userId,
    required this.items,
  });

  factory Cart.fromJson(Map<String, dynamic> json) {
    return Cart(
      id: json['_id'] as String,
      userId: json['user'] as String,
      items: (json['items'] as List)
          .map((item) => CartItem.fromJson(item as Map<String, 
           dynamic>)).toList(),
    );
  }
}

这是来自后端的json文件

{
    "updatedCart": {
        "_id": "66442f4",
        "user": "6628996ba",
        "items": [
            {
                "product": {
                    "_id": "66496e7e",
                    "user": "6696ba",
                    "vendor": "66311944",
                    "productName": "Yemlays Men's Fashion Comfortable Hoodie-black",
                    "productBrandName": "Yemlays",
                    "productPrice": "24,360",
                    "productDescription": "Welcome to our shop.",
                    "productDaysOfDelivery": "3",
                    "productType": "Clothing",
                    "productSize": "Regular",
                    "productQuantity": "",
                    "productImages": [
                        {
                            "productUrl": "https://_image/td3tadqj2n52vpelxntk.jpg",
                            "_id": "6640c8b824675c8aaa196e7f"
                        }
                    ],
                    "productAvailability": true,
                    "productStatus": "active",
                    "createdAt": "2024-05-12T13:48:40.612Z",
                    "updatedAt": "2024-05-12T13:48:40.612Z",
                    "__v": 0
                },
                "quantity": 2,
                "_id": "664454addc21f61eb83252f7"
            },
            {
                "product": {
                    "_id": "66403",
                    "user": "66ba",
                    "vendor": "66310e944",
                    "productName": "Yemlays Martin Boots Men's Tooling All-match High-top Shoes-beige",
                    "productBrandName": "Yemlays",
                    "productPrice": "9,467",
                    "productDescription": "This pair in addition to.",
                    "productDaysOfDelivery": "3",
                    "productType": "Foot Wares",
                    "productSize": "44",
                    "productQuantity": "",
                    "productImages": [
                        {
                            "productUrl": "https://t_image/xalew0pxva25ly49xb1w.jpg",
                            "_id": "6640c86224675c8aaa196e74"
                        },
                        {
                            "productUrl": "https://r9w.jpg",
                            "_id": "6640c86224675c8aaa196e75"
                        },
                        {
                            "productUrl": "https://re.jpg",
                            "_id": "6640c86224675c8aaa196e76"
                        },
                        {
                            "productUrl": "https://repg",
                            "_id": "6640c86224675c8aaa196e77"
                        }
                    ],
                    "productAvailability": true,
                    "productStatus": "active",
                    "createdAt": "2024-05-12T13:47:14.889Z",
                    "updatedAt": "2024-05-12T13:47:14.889Z",
                    "__v": 0
                },
                "quantity": 1,
                "_id": "664455b9dc21f61eb8325313"
            }
        ],
        "__v": 1
    }
}

我希望它能够映射数据，但我继续从 Json 获取数据 但在下面的代码中它打印了 

Response data is a Map;
这意味着 api 数据是 Map 数据， 同样对于这个 print("Response type: ${response.data.runtimeType}");，它打印了 
Response type: _Map<String, dynamic>

所以我真的不知道错误来自哪里......

Future<Cart?> addProductToCart(String productId, int quantity) async {
    try {
      const endpoint = "user/add_product_cart";
      final response = await apiProvider.post(endpoint, data: {
        'productId': productId,
        'quantity': quantity,
      });

      // Debugging information
      print("Response type: ${response.data.runtimeType}");
      print("Response data: ${response.data}");

      if (response.data is Map<String, dynamic>) {
        print("Response data is a Map");

        final updatedCartData =
            response.data['updatedCart'] as Map<String, dynamic>;
        print("updatedCart data type: ${updatedCartData.runtimeType}");

        return Cart.fromJson(updatedCartData);
      } else {
        print("Response data is not a Map");
        throw Exception('Unexpected response format');
      }
    } catch (e) {
      print("Error: $e");
      print('Error occures here');
      rethrow;
      // throw Exception('Failed to add product to cart: $e');
    }
  }
json flutter api dictionary
2个回答
0
投票

我想你的模型不适合 json 数据。您可以通过以下网站将 json 数据转换为类：https://javiercbk.github.io/json_to_dart/

我将你的 json 数据转换为模型和结果，如下所示：

class CartItem {
  UpdatedCart? updatedCart;

  CartItem({this.updatedCart});

  CartItem.fromJson(Map<String, dynamic> json) {
    updatedCart = json['updatedCart'] != null
        ? UpdatedCart.fromJson(json['updatedCart'])
        : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    if (updatedCart != null) {
      data['updatedCart'] = updatedCart!.toJson();
    }
    return data;
  }
}

class UpdatedCart {
  String? sId;
  String? user;
  List<Items>? items;
  int? iV;

  UpdatedCart({this.sId, this.user, this.items, this.iV});

  UpdatedCart.fromJson(Map<String, dynamic> json) {
    sId = json['_id'];
    user = json['user'];
    if (json['items'] != null) {
      items = <Items>[];
      json['items'].forEach((v) {
        items!.add(Items.fromJson(v));
      });
    }
    iV = json['__v'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['_id'] = sId;
    data['user'] = user;
    if (items != null) {
      data['items'] = items!.map((v) => v.toJson()).toList();
    }
    data['__v'] = iV;
    return data;
  }
}

class Items {
  Product? product;
  int? quantity;
  String? sId;

  Items({this.product, this.quantity, this.sId});

  Items.fromJson(Map<String, dynamic> json) {
    product =
        json['product'] != null ? Product.fromJson(json['product']) : null;
    quantity = json['quantity'];
    sId = json['_id'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    if (product != null) {
      data['product'] = product!.toJson();
    }
    data['quantity'] = quantity;
    data['_id'] = sId;
    return data;
  }
}

class Product {
  String? sId;
  String? user;
  String? vendor;
  String? productName;
  String? productBrandName;
  String? productPrice;
  String? productDescription;
  String? productDaysOfDelivery;
  String? productType;
  String? productSize;
  String? productQuantity;
  List<ProductImages>? productImages;
  bool? productAvailability;
  String? productStatus;
  String? createdAt;
  String? updatedAt;
  int? iV;

  Product(
      {this.sId,
      this.user,
      this.vendor,
      this.productName,
      this.productBrandName,
      this.productPrice,
      this.productDescription,
      this.productDaysOfDelivery,
      this.productType,
      this.productSize,
      this.productQuantity,
      this.productImages,
      this.productAvailability,
      this.productStatus,
      this.createdAt,
      this.updatedAt,
      this.iV});

  Product.fromJson(Map<String, dynamic> json) {
    sId = json['_id'];
    user = json['user'];
    vendor = json['vendor'];
    productName = json['productName'];
    productBrandName = json['productBrandName'];
    productPrice = json['productPrice'];
    productDescription = json['productDescription'];
    productDaysOfDelivery = json['productDaysOfDelivery'];
    productType = json['productType'];
    productSize = json['productSize'];
    productQuantity = json['productQuantity'];
    if (json['productImages'] != null) {
      productImages = <ProductImages>[];
      json['productImages'].forEach((v) {
        productImages!.add(ProductImages.fromJson(v));
      });
    }
    productAvailability = json['productAvailability'];
    productStatus = json['productStatus'];
    createdAt = json['createdAt'];
    updatedAt = json['updatedAt'];
    iV = json['__v'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['_id'] = sId;
    data['user'] = user;
    data['vendor'] = vendor;
    data['productName'] = productName;
    data['productBrandName'] = productBrandName;
    data['productPrice'] = productPrice;
    data['productDescription'] = productDescription;
    data['productDaysOfDelivery'] = productDaysOfDelivery;
    data['productType'] = productType;
    data['productSize'] = productSize;
    data['productQuantity'] = productQuantity;
    if (productImages != null) {
      data['productImages'] = productImages!.map((v) => v.toJson()).toList();
    }
    data['productAvailability'] = productAvailability;
    data['productStatus'] = productStatus;
    data['createdAt'] = createdAt;
    data['updatedAt'] = updatedAt;
    data['__v'] = iV;
    return data;
  }
}

class ProductImages {
  String? productUrl;
  String? sId;

  ProductImages({this.productUrl, this.sId});

  ProductImages.fromJson(Map<String, dynamic> json) {
    productUrl = json['productUrl'];
    sId = json['_id'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['productUrl'] = productUrl;
    data['_id'] = sId;
    return data;
  }
}
0
投票

我希望它能够映射数据，但我不断获取数据 fromJson 但在下面的代码中它打印了 Response data is a Map; 这意味着 api 数据是 Map 数据...

正确，整个响应是一张地图。

但是，

type String is not a subtype of type Map<String, dynamic>
的误差可以与主响应无关，它可以是主响应的子类型之一，例如
Product
或其任何子类型。在某个地方，响应中的对象（地图）被反序列化为字符串。

解决此类问题的一个好方法是为响应中的每个对象创建一个新模型（子类型）：

class ResponseModel {
  UpdatedCart? updatedCart;

  ResponseModel({this.updatedCart});

  ResponseModel.fromJson(Map<String, dynamic> json) {
    updatedCart = json['updatedCart'] != null
        ? UpdatedCart.fromJson(json['updatedCart'])
        : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    if (updatedCart != null) {
      data['updatedCart'] = updatedCart!.toJson();
    }
    return data;
  }
}

class UpdatedCart {
  String? sId;
  String? user;
  List<Items>? items;
  int? iV;

  UpdatedCart({this.sId, this.user, this.items, this.iV});

  UpdatedCart.fromJson(Map<String, dynamic> json) {
    sId = json['_id'];
    user = json['user'];
    if (json['items'] != null) {
      items = <Items>[];
      json['items'].forEach((v) {
        items!.add(Items.fromJson(v));
      });
    }
    iV = json['__v'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['_id'] = sId;
    data['user'] = user;
    if (items != null) {
      data['items'] = items!.map((v) => v.toJson()).toList();
    }
    data['__v'] = iV;
    return data;
  }
}

class Items {
  Product? product;
  int? quantity;
  String? sId;

  Items({this.product, this.quantity, this.sId});

  Items.fromJson(Map<String, dynamic> json) {
    product =
        json['product'] != null ? Product.fromJson(json['product']) : null;
    quantity = json['quantity'];
    sId = json['_id'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    if (product != null) {
      data['product'] = product!.toJson();
    }
    data['quantity'] = quantity;
    data['_id'] = sId;
    return data;
  }
}

class Product {
  String? sId;
  String? user;
  String? vendor;
  String? productName;
  String? productBrandName;
  String? productPrice;
  String? productDescription;
  String? productDaysOfDelivery;
  String? productType;
  String? productSize;
  String? productQuantity;
  List<ProductImages>? productImages;
  bool? productAvailability;
  String? productStatus;
  String? createdAt;
  String? updatedAt;
  int? iV;

  Product(
      {this.sId,
      this.user,
      this.vendor,
      this.productName,
      this.productBrandName,
      this.productPrice,
      this.productDescription,
      this.productDaysOfDelivery,
      this.productType,
      this.productSize,
      this.productQuantity,
      this.productImages,
      this.productAvailability,
      this.productStatus,
      this.createdAt,
      this.updatedAt,
      this.iV});

  Product.fromJson(Map<String, dynamic> json) {
    sId = json['_id'];
    user = json['user'];
    vendor = json['vendor'];
    productName = json['productName'];
    productBrandName = json['productBrandName'];
    productPrice = json['productPrice'];
    productDescription = json['productDescription'];
    productDaysOfDelivery = json['productDaysOfDelivery'];
    productType = json['productType'];
    productSize = json['productSize'];
    productQuantity = json['productQuantity'];
    if (json['productImages'] != null) {
      productImages = <ProductImages>[];
      json['productImages'].forEach((v) {
        productImages!.add(ProductImages.fromJson(v));
      });
    }
    productAvailability = json['productAvailability'];
    productStatus = json['productStatus'];
    createdAt = json['createdAt'];
    updatedAt = json['updatedAt'];
    iV = json['__v'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['_id'] = sId;
    data['user'] = user;
    data['vendor'] = vendor;
    data['productName'] = productName;
    data['productBrandName'] = productBrandName;
    data['productPrice'] = productPrice;
    data['productDescription'] = productDescription;
    data['productDaysOfDelivery'] = productDaysOfDelivery;
    data['productType'] = productType;
    data['productSize'] = productSize;
    data['productQuantity'] = productQuantity;
    if (productImages != null) {
      data['productImages'] =
          productImages!.map((v) => v.toJson()).toList();
    }
    data['productAvailability'] = productAvailability;
    data['productStatus'] = productStatus;
    data['createdAt'] = createdAt;
    data['updatedAt'] = updatedAt;
    data['__v'] = iV;
    return data;
  }
}

class ProductImages {
  String? productUrl;
  String? sId;

  ProductImages({this.productUrl, this.sId});

  ProductImages.fromJson(Map<String, dynamic> json) {
    productUrl = json['productUrl'];
    sId = json['_id'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['productUrl'] = productUrl;
    data['_id'] = sId;
    return data;
  }
}


ResponseModel
是解析整个响应的输出，其中包含响应中每个对象的子类型。

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