Flutter _TypeError（类型'List< dynamic>'不是类型'Map< String，dynamic>'的子类型） [英] Flutter _TypeError (type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>')

问题描述

我是陌生的，遇到类型错误。我正在尝试使用json自动序列化。

I am new to flutter and getting type error. I am trying to use json automated serializations.

在做一些表情之后，看起来像是这样

AFTER DOING SOME TWEAKS HERE IS HOW IT LOOKS LIKE

这是我尝试从api获取数据的方式

Here is how I am trying to get the data from api

  Future getMyProduct() async {
     final res = await http.get('url');
     final data = json.decode(res.body);
     BaseResponse req = new BaseResponse.fromJson(data);
     return req;
  }

我的 BaseResponse 类看起来像这样

import 'package:dynamicapp/model/model.dart';
import 'package:json_annotation/json_annotation.dart';

part 'response.g.dart';

@JsonSerializable()
class BaseResponse extends Object {
    final int id;

final int sellingPrice;
final int totalStock;
final String productName;
final String productDesc;
final List<Image> images;

BaseResponse(this.id, this.sellingPrice, this.totalStock, this.productName,
    this.productDesc, this.images);

factory BaseResponse.fromJson(Map<String, dynamic> json) => _$BaseResponseFromJson(json);

Map<String, dynamic> toJson() => _$BaseResponseToJson(this);
}

@JsonSerializable()
 class Image extends Object {
    final int id;
    final String image;
//  final int product_id;

   Image(this.id, this.image);
factory Image.fromJson(Map<String, dynamic> json) => _$ImageFromJson(json);
   Map<String, dynamic> toJson() => _$ImageToJson(this);
}

有人可以帮我这个忙吗？我被困在这里。一直在尝试不同的方法，但没有任何效果。谢谢。

Could anyone please help me with this. I am stuck here. Have been trying different methods but none working. Thank you.

推荐答案

看来 data 是 List< dynamic> ，然后 data.map（someFunc）.toList（）将把每个数据元素传递给 someFunc 并将其重新组成返回类型为 someFunc 的列表（您可能希望将其设为 BaseResponse ）。这告诉您 someFunc 必须是一个具有 dynamic 动态并返回 BaseResponse 。

It looks like data is a List<dynamic>, then data.map(someFunc).toList() will take each element of data pass it to someFunc and form it back into a list of the return type of someFunc (which you will presumably want to be BaseResponse). Which tells you that someFunc needs to be a function that takes dynamic and returns BaseResponse.

您想写这样的东西：

  final data = json.decode(res.body);
  List<BaseResponse> responses =
      data.map((j) => BaseResponse.fromJson(j)).toList();

这篇关于Flutter _TypeError（类型'List< dynamic>'不是类型'Map< String，dynamic>'的子类型）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！