deserialize json object does not work

Question

I want to deserialize my json object to my student class

var result = JsonConvert.DeserializeObject<Student>(data);

My json data

{  
"student":{  
  "fname":"997544",
  "lname":"997544",
  "subject":"IT",
  "grade":"F"
}
}

My student class

[Serializable]
public class Student
{
    [JsonProperty("fname")]
    public string FirstName{ get; set; }
    [JsonProperty("lname")]
    public string LastName{ get; set; }
    [JsonProperty("subject")]
    public string Subject { get; set; }
    [JsonProperty("grade")]
    public string Grade { get; set; }
 }

The code does not work, the error says:

Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.

Answer 1

Your JSON string currently represents an object with an inner object property named Student. If you want to deserialize to your Student object your JSON string should look like this:

{  
   "fname":"997544",
   "lname":"997544",
   "subject":"IT",
   "grade":"F"
}

If it's not easy to change your JSON you could also use JObject to help you like so:

var jobject = JObject.Parse(jsonData);
var student = JsonConvert.DeserializeObject<Student>(jobject["student"].ToString());

Or as others have pointed out you can simply create another class wrapper and deserialize directly to that.

Answer 2

if you have to use your downloaded json then you need to create another model class for it

[Serializable]
public class Student
{
    [JsonProperty("fname")]
    public string FirstName{ get; set; }
    [JsonProperty("lname")]
    public string LastName{ get; set; }
    [JsonProperty("subject")]
    public string Subject { get; set; }
    [JsonProperty("grade")]
    public string Grade { get; set; }
}

[Serializable]
public class NewModel
{
    public Student Student { get; set; }
}

then deserialize

var result = JsonConvert.DeserializeObject<NewModel>(data);