Saving json array to c# class object

Question

I have to assign json array of string to a c# class. I have done like below. But I got an exceptio

Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'LoggedInUserDetails' because the type requires a JSON object (e.g. {\"name\":\"value\"}) to deserialize correctly.\r\nTo 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 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.\r\nPath '', line 1, position 1."}

public class LoggedInUserDetails
{
    public string login_user_name
    {
        get; set;
    }

    public string login_user_id
    {
        get; set;
    }
}

 var GetResponse = await response2.Content.ReadAsStringAsync();
//"[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]"
 LoggedInUserDetails obj = JsonConvert.DeserializeObject<LoggedInUserDetails>(GetResponse);
 Variables.login_user_name = obj.login_user_name;
 Variables.login_user_id= obj.login_user_id;

your json is a list, so var obj = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(GetResponse); — JeePakaJP
– JeePakaJP, Commented Jan 29, 2020 at 9:16

Mihai Alexandru-Ionut · Accepted Answer · 2020-01-29 09:27:35Z

3

You should deserialize the json string to an IEnumerable collection or Array.

 var content = await response2.Content.ReadAsStringAsync();
 var result = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(content);

edited Jan 29, 2020 at 9:27

answered Jan 29, 2020 at 9:18

Mihai Alexandru-Ionut

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1 Comment

Cid Over a year ago

I wouldn't say that OP should deserialize to a List, but could. One can deserialize to any collection, such as LoggedInUserDetails[], IEnumerable<LoggedInUserDetails> and so on...

Cid · Accepted Answer · 2020-01-29 09:20:52Z

0

It because of the '[]', which stores it as a array of results. You should be able to do something like the following:

LoggedInUserDetails obj = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(GetResponse);

where you try to deserialize object as an list. The list will only contain 1 object.

full example:

public class LoggedInUserDetails
{
    public string login_user_name
    {
        get; set;
    }

    public string login_user_id
    {
        get; set;
    }
}

 var GetResponse = await response2.Content.ReadAsStringAsync();
//"[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]"
 List<LoggedInUserDetails> obj = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(GetResponse);
 Variables.login_user_name = obj[0].login_user_name;
 Variables.login_user_id= obj[0].login_user_id;

edited Jan 29, 2020 at 9:20

Cid

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answered Jan 29, 2020 at 9:19

Kiksen

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Comments

Marco Salerno · Accepted Answer · 2020-01-29 09:27:58Z

0

This way:

LoggedInUserDetails obj = JsonConvert.DeserializeObject<LoggedInUserDetails[]>(GetResponse).FirstOrDefault() ?? throw new Exception("User not found.");
Variables.login_user_name = obj.login_user_name;
Variables.login_user_id = obj.login_user_id;

Your result was an array containing 1 object, so you just had to convert it to an array of your desired object and take the first.

edited Jan 29, 2020 at 9:27

answered Jan 29, 2020 at 9:20

Marco Salerno

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2 Comments

Marco Salerno Over a year ago

Guys instead of editing my answer, read the code please. Your edits were completely wrong.

Cid Over a year ago

Indeed, my bad.

Saif · Accepted Answer · 2020-01-29 10:27:28Z

0

Since you are using array, then it should deserialize array to list public class Test { public string login_user_name {get; set;} public string login_user_id { get; set;} }

string js =  "[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]";
var result  =  JsonConvert.DeserializeObject<List<Test>>(js);
foreach(var ob in result)
{
  Console.WriteLine(ob.login_user_name);
  Console.WriteLine(ob.login_user_id);
}

output

Rahul
43

edited Jan 29, 2020 at 10:27

answered Jan 29, 2020 at 9:34

Saif

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