使用http包获取数据时遇类型不匹配错误：_InternalLinkedHashMap无法转为String

错误type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'String'的核心原因是：WordPress REST API返回的title和content并非直接字符串，而是包含rendered字段的嵌套对象，你的模型直接将其赋值给String类型变量导致类型不匹配。

以下是保留现有Future函数前提下的修复步骤：

1. 修正NewsModel模型类 #

修改fromJson构造函数，正确解析嵌套的title和content字段：

class NewsModel {
  late int id;
  late String date;
  late String status;
  late String type;
  late String link;
  late String title;
  late String content;

  NewsModel({
    required this.id,
    required this.date,
    required this.status,
    required this.type,
    required this.link,
    required this.title,
    required this.content,
  });

  NewsModel.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    date = json['date'];
    status = json['status'];
    type = json['type'];
    link = json['link'];
    // 解析嵌套的title对象，取rendered字段
    title = json['title']['rendered'];
    // 解析嵌套的content对象，取rendered字段
    content = json['content']['rendered'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['id'] = id;
    data['date'] = date;
    data['status'] = status;
    data['type'] = type;
    data['link'] = link;
    data['title'] = title;
    data['content'] = content;
    return data;
  }
}

2. 修正NewsController控制器 #

将返回的原始JSON列表转换为List<NewsModel>，增强类型安全性：

import 'dart:convert';
import 'package:http/http.dart' as http;
import 'your_model_path.dart'; // 替换为你的NewsModel文件路径

class NewsController {
  String url = "https://wrestlingworld.co/wp-json/wp/v2/posts?categories=22";
  
  Future<List<NewsModel>> getNews() async {
    try {
      var response = await http.get(Uri.parse(url));
      if (response.statusCode == 200) {
        // 将JSON数组转换为NewsModel列表
        List<dynamic> jsonList = json.decode(response.body);
        return jsonList.map((json) => NewsModel.fromJson(json)).toList();
      } else {
        throw Exception("请求处理错误，状态码: ${response.statusCode}");
      }
    } catch (e) {
      print(e);
      throw Exception("控制器请求错误");
    }
  }
}

3. 修正FutureBuilder数据获取代码 #

使用转换后的NewsModel对象获取数据：

FutureBuilder<List<NewsModel>>(
  future: newsController.getNews(),
  builder: (context, snapShot) {
    if (snapShot.hasData) {
      return Padding(
        padding: const EdgeInsets.all(8.0),
        child: ListView.builder(
          scrollDirection: Axis.vertical,
          shrinkWrap: true,
          itemCount: snapShot.data?.length ?? 0,
          itemBuilder: (context, index) {
            NewsModel news = snapShot.data![index];
            return NewsCard(title: news.title);
          },
        ),
      );
    } else if (snapShot.hasError) {
      return Center(child: Text("${snapShot.error}"));
    } else {
      return const Center(child: CircularProgressIndicator());
    }
  },
)

额外说明 #

• WordPress REST API的文章字段中，title、content、excerpt均为包含rendered（渲染后文本）和raw（原始文本）的对象，需根据需求取对应字段。
• 控制器中使用throw Exception替代return Future.error，更符合Dart异步错误处理规范，同时保留了Future函数的结构。

内容的提问来源于stack exchange，提问作者sakib Ovi