未处理的异常：“String”类型不是“List”类型的子类型<dynamic> &#39;

Question

I'm trying to parse the images from images from the json response, but I'm getting as error stating as Unhandled Exception: type 'String' is not a subtype of type 'List'

{
    "status": true,
    "record": {
        "adid": "3",
        "adsubcatid": "7",
        "aduserid": "2",
        "adname": "wfw fw",
        "adcoverimg": "http://codecell.in/girrivi/assets/adcover/ic_service_search.png",
        "addesc": "e fe fe ",
        "ads_price": "5000",
        "ads_location": "mysuru",
        "created_date": "13/10/2020",
        "user_name": "sunil",
        "images": "{'adsimg_img':'http://codecell.in/girrivi/assets/adimgs/carpenter.png'},{'adsimg_img':'http://codecell.in/girrivi/assets/adimgs/electrician.png'},{'adsimg_img':'http://codecell.in/girrivi/assets/adimgs/gardner.png'}"
    }
}

List images;
Future<String> getProductDetails() async {
    String productDetailsUrl = Constant.productDetailsUrl+widget.id;
    print(productDetailsUrl);
    Map<String, String> headers = {'Content-Type' : 'application/json'};

    final response = await http.get(productDetailsUrl, headers: headers);
    print(response.body);
    if(response.statusCode == 200){
      jsonResponse = json.decode(response.body);
      print('Response in Profile Screen: ' + response.body);
      print("Price - "+jsonResponse['record']['ads_price']);
      setState(() {
        price = jsonResponse['record']['ads_price'];
        title = jsonResponse['record']['adname'];
        description = jsonResponse['record']['addesc'];
        location = jsonResponse['record']['ads_location'];
        publishedOn = jsonResponse['record']['created_date'];
        postedBy = jsonResponse['record']['user_name'];
        adId = jsonResponse['record']['adid'];
        postedById = jsonResponse['record']['aduserid'];
        images = jsonResponse['record']['images'];
      });
    }
  }

I am getting all the details in the right way except the images

Answer 1

As I see in your images response you have this {'adsimg_img': 'some_url'}.

So I would do like this in your code

setState(() {
  .
  .
  .
  adId = jsonResponse['record']['adid'];
  postedById = jsonResponse['record']['aduserid'];
  images = (jsonResponse['record']['images'] as List)
    ?.map((i) => i['adsimg_img'])
    ?.toList();
});

So images at the end will look like ['url1', 'url2', ...] // List of Strings

I didn't tested it but it should do the trick :)

Answer 2

In the json response snippet that you have added, the value of images should be an array, but it is in double quotes which is a basically string.

If you put that snippet into a jsonValidator like this one, it shows that the value of the key images is a string, rather than the array that you are expecting.

An array of objects in json is formatted like in this one

{
  "user_name": "sunil",
  "images": [
    {
      "adsimg_img":"http://codecell.in/girrivi/assets/adimgs/carpenter.png"
    },
    {
      "adsimg_img":"http://codecell.in/girrivi/assets/adimgs/carpenter.png"
    },
    {
      "adsimg_img":"http://codecell.in/girrivi/assets/adimgs/carpenter.png"
    }
  ]
}