Flutter 颤振Json未处理异常：类型'_内部链接dhashmap<；字符串，动态>'；不是类型为'；Iterable<；动态>'；

类别 错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型

  class Category {
  int id;
  String categoryName;
  String seoUrl;


  Category(this.id,this.categoryName,this.seoUrl);

  Category.fromJson(Map json){
    id = json["id"];
    categoryName = json["categoryName"];
    seoUrl = json["seoUrl"];
  }

  Map toJson(){
    return {
      "id": id,
      "categoryName": categoryName,
      "seoUrl": seoUrl
    };
  }
}

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http_demo/data/api/category_api.dart';
import 'package:http_demo/models/category.dart';

class MainScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MainScreenState();
  }
}

class MainScreenState extends State {
  List<Category> categories = List<Category>();
  List<Widget> categoryWidgets = List<Widget>();

  @override
  void initState() {
    getCategoriesFromApi();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          "Alışveriş Sistemi",
          style: TextStyle(color: Colors.white),
        ),
        backgroundColor: Colors.blueGrey,
        centerTitle: true,
      ),
      body: Padding(
        padding: EdgeInsets.all(10.0),
        child: Column(
          children: <Widget>[
            SingleChildScrollView(
              scrollDirection: Axis.horizontal,
              child: Row(
                children: categoryWidgets,
              ),
            )
          ],
        ),
      ),
    );
  }

  void getCategoriesFromApi() {
    CategoryApi.getCategories().then((response) {
      setState(() {
        Iterable list = json.decode(response.body);
        //categories = list.map((category) => Category.fromJson(category)).toList();
        this.categories = List<Category>.from(list.map((model)=> Category.fromJson(model)));
        getCategoryWidgets();
      });
    });
  }

  List<Widget> getCategoryWidgets() {
    for (int i = 0; i < categories.length; i++) {
      categoryWidgets.add(getCategoryWidget(categories[i]));
    }
    return categoryWidgets;
  }

  Widget getCategoryWidget(Category category) {
    return FlatButton(
      onPressed: null,
      child: Text(
        category.categoryName,
        style: TextStyle(color: Colors.blueGrey),
      ),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(15.0),
        side: BorderSide(color: Colors.lightGreenAccent),
      ),
    );
  }
}

类主屏幕

错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型

  class Category {
  int id;
  String categoryName;
  String seoUrl;


  Category(this.id,this.categoryName,this.seoUrl);

  Category.fromJson(Map json){
    id = json["id"];
    categoryName = json["categoryName"];
    seoUrl = json["seoUrl"];
  }

  Map toJson(){
    return {
      "id": id,
      "categoryName": categoryName,
      "seoUrl": seoUrl
    };
  }
}

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http_demo/data/api/category_api.dart';
import 'package:http_demo/models/category.dart';

class MainScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MainScreenState();
  }
}

class MainScreenState extends State {
  List<Category> categories = List<Category>();
  List<Widget> categoryWidgets = List<Widget>();

  @override
  void initState() {
    getCategoriesFromApi();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          "Alışveriş Sistemi",
          style: TextStyle(color: Colors.white),
        ),
        backgroundColor: Colors.blueGrey,
        centerTitle: true,
      ),
      body: Padding(
        padding: EdgeInsets.all(10.0),
        child: Column(
          children: <Widget>[
            SingleChildScrollView(
              scrollDirection: Axis.horizontal,
              child: Row(
                children: categoryWidgets,
              ),
            )
          ],
        ),
      ),
    );
  }

  void getCategoriesFromApi() {
    CategoryApi.getCategories().then((response) {
      setState(() {
        Iterable list = json.decode(response.body);
        //categories = list.map((category) => Category.fromJson(category)).toList();
        this.categories = List<Category>.from(list.map((model)=> Category.fromJson(model)));
        getCategoryWidgets();
      });
    });
  }

  List<Widget> getCategoryWidgets() {
    for (int i = 0; i < categories.length; i++) {
      categoryWidgets.add(getCategoryWidget(categories[i]));
    }
    return categoryWidgets;
  }

  Widget getCategoryWidget(Category category) {
    return FlatButton(
      onPressed: null,
      child: Text(
        category.categoryName,
        style: TextStyle(color: Colors.blueGrey),
      ),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(15.0),
        side: BorderSide(color: Colors.lightGreenAccent),
      ),
    );
  }
}

导入“dart:convert”；
进口“包装：颤振/材料.省道”；
导入“包：http_demo/data/api/category_api.dart”；
导入“包：http_demo/models/category.dart”；
类MainScreen扩展StatefulWidget{
@凌驾
状态createState（）{
返回MainScreenState（）；
}
}
类MainScreenState扩展了状态{
列表类别=列表（）；
List categoryWidgets=List（）；
@凌驾
void initState（）{
getCategoriesFromApi（）；
super.initState（）；
}
@凌驾
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar(
标题：正文(
“安全系统”，
样式：TextStyle（颜色：Colors.white），
),
背景颜色：颜色。蓝灰色，
标题：对，
),
主体：填充物(
填充：所有边缘设置（10.0），
子：列(
儿童：[
SingleChildScrollView(
滚动方向：轴水平，
孩子：排(
子类：categoryWidgets，
),
)
],
),
),
);
}
void getCategoriesFromApi（）{
CategoryApi.getCategories（）.then（（响应）{
设置状态（）{
Iterable list=json.decode（response.body）；
//categories=list.map（（category）=>category.fromJson（category））.toList（）；
this.categories=List.from（List.map（（model）=>Category.fromJson（model））；
getCategoryWidgets（）；
});
});
}
列表getCategoryWidgets（）{
对于（int i=0；i

错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型。

错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型 错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型 错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型

---

错误：未处理的异常：类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型

请在转换JSON后检查响应

  class Category {
  int id;
  String categoryName;
  String seoUrl;


  Category(this.id,this.categoryName,this.seoUrl);

  Category.fromJson(Map json){
    id = json["id"];
    categoryName = json["categoryName"];
    seoUrl = json["seoUrl"];
  }

  Map toJson(){
    return {
      "id": id,
      "categoryName": categoryName,
      "seoUrl": seoUrl
    };
  }
}

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http_demo/data/api/category_api.dart';
import 'package:http_demo/models/category.dart';

class MainScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MainScreenState();
  }
}

class MainScreenState extends State {
  List<Category> categories = List<Category>();
  List<Widget> categoryWidgets = List<Widget>();

  @override
  void initState() {
    getCategoriesFromApi();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          "Alışveriş Sistemi",
          style: TextStyle(color: Colors.white),
        ),
        backgroundColor: Colors.blueGrey,
        centerTitle: true,
      ),
      body: Padding(
        padding: EdgeInsets.all(10.0),
        child: Column(
          children: <Widget>[
            SingleChildScrollView(
              scrollDirection: Axis.horizontal,
              child: Row(
                children: categoryWidgets,
              ),
            )
          ],
        ),
      ),
    );
  }

  void getCategoriesFromApi() {
    CategoryApi.getCategories().then((response) {
      setState(() {
        Iterable list = json.decode(response.body);
        //categories = list.map((category) => Category.fromJson(category)).toList();
        this.categories = List<Category>.from(list.map((model)=> Category.fromJson(model)));
        getCategoryWidgets();
      });
    });
  }

  List<Widget> getCategoryWidgets() {
    for (int i = 0; i < categories.length; i++) {
      categoryWidgets.add(getCategoryWidget(categories[i]));
    }
    return categoryWidgets;
  }

  Widget getCategoryWidget(Category category) {
    return FlatButton(
      onPressed: null,
      child: Text(
        category.categoryName,
        style: TextStyle(color: Colors.blueGrey),
      ),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(15.0),
        side: BorderSide(color: Colors.lightGreenAccent),
      ),
    );
  }
}

void getCategoriesFromApi() {
  CategoryApi.getCategories().then((response) {
    setState(() {
      var list = json.decode(response.body);
      //categories = list.map((category) => Category.fromJson(category)).toList();
      if (list is List) {
        this.categories = list.map((e) => Category.fromJson(e)).toList();
        getCategoryWidgets();
      } else {
        print('response is not list');
      }
    });
  });
}

---

你能分享response.body吗？我得到了文本“response is not list”import“package:http/http.dart”作为http；类CategoryApi{static Future getCategories（）{return http.get（“）；}}}是。您可以检查响应。print（response.body）；类Category{int id；String categoryName；String seoUrl；Category（this.id，this.categoryName，this.seoUrl）；Category.fromJson（Map json）{id=json[“id”]；categoryName=json[“categoryName”]；seoUrl=json[“seoUrl”]；}映射到json（）{return{“id”：id，“categoryName”：categoryName，“seoUrl”：seoUrl}；}}我正在使用bluestack。