未处理的异常：类型“List<dynamic>”不是 dart/flutter 中“Map<String, dynamic>”类型的子类型

Question

我可以解码来自服务器的响应，但我不知道这是什么错误：\

这是我在 showproduct 类中的请求代码：

if (response.statusCode == 200) {

      setState(() {
        var bodybytedecoded= jsonDecode(utf8.decode(response.bodyBytes));

  final product= ProductModel.fromJson(bodybytedecoded); // console shows error come from this line
        print(product);
        }
      });
    }
    else {
      print(response.reasonPhrase);
    }

在我的模型类中，我有：

class ProductModel{
   final  int id;
   final  String name;
   final String regular_price;
   final String description;
   final List<ImageModel> image;

  ProductModel({ required this.id,required this.name,required this.regular_price,  required this.description,required this.image});

  factory ProductModel.fromJson(Map<String,dynamic> json){
    final name = json["name"];
    final id = json ["id"];
    final regular_price = json["regular_price"];
    final description = json["description"];
    final image = json["image"];
    return ProductModel(id: id, name: name, regular_price: regular_price, description: description, image: image);
  }

  Map<String,dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data["id"] = this.id;
    data["name"] = this.name;
    data["regular_rice"] = this.regular_price;
    data["description"] = this.description;
    data["image"] = this.image;
    return data;
  }
}

class ImageModel{
   final String src;
  ImageModel({required this.src});
  factory ImageModel.fromJson(Map<String,dynamic> json ){
    return ImageModel(src:  json["src"]);
  }


}

我不知道这个错误是为了什么，我的模型类有什么问题吗？还是我的要求？ 如果有人能告诉我一个真正的方法，我将不胜感激。

这是完整的错误：

E/flutter (31338): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'
E/flutter (31338): #0      _ShowProductState.FetchItems.<anonymous closure> (package:mystore/ProductPages/showproduct.dart:219:46)
E/flutter (31338): #1      State.setState (package:flutter/src/widgets/framework.dart:1088:30)
E/flutter (31338): #2      _ShowProductState.FetchItems (package:mystore/ProductPages/showproduct.dart:215:7)
E/flutter (31338): <asynchronous suspension>
E/flutter (31338): 

这是来自服务器的 json 正文：

[
    {
        "id": 56012,
        "name": "a name",
        "slug": "a slug",
        "description": "<p>آب آشامیدنی پیورلایف 1/5 لیتری نستله</p>\n",
        "regular_price": "45000",
        "sale_price": "45000",
        "tags": [],
        "images": [
            {
                "id": 56043,
                "src": "pic link",
                "name": "A name",
            }
        ],
    },
]

Answer 1

将此行添加到您的 ProductModel

List<ProductModel> productFromJson(String str) => List<ProductModel>.from(jsonDecode(str).map((x) => ProductModel.fromJson(x)));

并将您的代码更改为这样

if (response.statusCode == 200) {

      setState(() {
        var bodybytedecoded= jsonDecode(utf8.decode(response.bodyBytes));

  final product= productFromJson(bodybytedecoded); // console shows error come from this line
        print(product);
        }
      });
    }
    else {
      print(response.reasonPhrase);
    }

Answer 2

问题是您正在尝试将列表映射到地图将此行更改为

 final product= ProductModel.fromJson(bodybytedecoded);

到

var bodybytedecoded= jsonDecode(utf8.decode(response.bodyBytes));
final List<ProductModel> products = bodybytedecoded
          .map((model) => ProductModel.fromJson(model));

顺便说一句，toJson 中有一个错字

 data["regular_rice"] = this.regular_price;

Answer 3

您可以通过解码数据并将值存储在列表中来简单地做到这一点。

 var decodedResponse= jsonDecode(resonse.body); 

List<ProductModel> items=[];
  decodedResponse.forEach((e){
    items.add(ProductModel.fromJson(e));
  });