Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'portal.Models.SubProjectVie-CodePudding

I've got this simple code that will consume api json array from a url.

public ActionResult ViewRecord()
        {

            ViewBag.Title = "- Geotagging Sub Project Record.";
            var webClient = new WebClient();
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls
                                     | SecurityProtocolType.Tls11
                                     | SecurityProtocolType.Tls12;
            webClient.Headers.Add(HttpRequestHeader.Cookie, "cookievalue");
            string objJson = webClient.DownloadString(@"https://test.com/api/lib_region");

             //here we will map the Json to C# class
            Models.SubProjectViewRecord oop = JsonConvert.DeserializeObject<Models.SubProjectViewRecord>(objJson);                                                                                                               
            return View(oop);
            
    }

my model

namespace portal.Models
{
    public class SubProjectViewRecord
    {
        public string Name { get; set; }
        public int Id { get; set; }
    }
}

The error of the code above is:

'Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'portal.Models.SubProjectViewRecord' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.
To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List<T> that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.
Path '', line 1, position 1.'

then these are the fixes I apply to model as some reply being posted.

public class SubProjectViewRecord
        {
            public List<string> Name { get; set; }
            public List<int> Id { get; set; }
        }

to this line:

Models.SubProjectViewRecord oop = JsonConvert.DeserializeObject<List<Models.SubProjectViewRecord>>(objJson);

but the error raised:

Cannot implicitly convert type 'System.Collections.Generic.List<portal.Models.SubProjectViewRecord>' to 'portal.Models.SubProjectViewRecord'

Thanks in advance.

CodePudding user response：

Apparently looks like from the error that there are multiple items in the array that is why there is any array returned from the api reponse. you can use a List<T> for it and the code for it would be like :

List<Models.SubProjectViewRecord> oop = JsonConvert.DeserializeObject<List<Models.SubProjectViewRecord>>(objJson);

While your model would be below assuming that the json array elements are of json object with Id and Name members in it:

public class SubProjectViewRecord
{
    public string Name { get; set; }
    public int Id { get; set; }
}

CodePudding user response：

First of all, you'll need to know how is your data returned by your JSON. So, if you have something like that:

[
  {
    "name": "",
    "id": ""
  }
]

What you'll need is a list of a class that implements a structure like that (like SubProjectViewRecord). So, you'll have something like that:

List<SubProjectViewRecord> oop = JsonConvert.DeserializeObject<List<SubProjectViewRecord>>(objJson);

And if you see, that is exactly what your error says. It says: "I cannot assign a List to a SubProjectViewRecord variable".

So, just be sure of:

Your class matches exactly with your JSON structure.
The class that you provide for the deserialization (the generic that you pass on DeserializeObject) is the same as the variable that will receive the deserialization.