Deserializing JToken content to an Object

Question

I want to deserialize JToken content to an object (User). How am I able to do this?

Here is my json string:

string json = @"[{""UserId"":0,""Username"":""jj.stranger"",""FirstName"":""JJ"",""LastName"":""stranger""}]";

This being sent to an api parameter as JToken.

User class:

public class user
{
    public int UserId {get; set;}
    public string Username {get; set;}
    public string FirstName {get; set;}
    public string LastName {get; set;}
}

Web Api Method:

public IHttpActionResult Post([FromBody]JToken users)
{
      UserModel.SaveUser(users);
      //...
}

API Invocation in Salesforce:

string json = '[{"UserId":0,"Username":"jj.stranger","FirstName":"JJ","LastName":"stranger"}]';
HttpRequest req = new HttpRequest();
HttpResponse res = new HttpResponse();
Http http = new Http();
            
req.setEndpoint('test.com/api/UserManagement');
req.setMethod('POST');
req.setBody(json);
req.setHeader('Content-Type', 'application/json');
            
try {
    res = http.send(req);
} catch(System.CalloutException e) {
    System.debug('Callout error:' + e);
}
            
System.debug(res.getBody());

Solution

You can use JToken.ToObject generic method. http://www.nudoq.org/#!/Packages/Newtonsoft.Json/Newtonsoft.Json/JToken/M/ToObject(T)

Server API Code:

 public void Test(JToken users)
 {
     var usersArray = users.ToObject<User[]>();
 }

Here is the client code I use.

string json = "[{\"UserId\":0,\"Username\":\"jj.stranger\",\"FirstName\":\"JJ\",\"LastName\":\"stranger\"}]";
HttpClient client = new HttpClient();
var result = client.PostAsync(@"http://localhost:50577/api/values/test", new StringContent(json, Encoding.UTF8, "application/json")).Result;

The object gets converted to Users array without any issues.

Comments

[Robert Mansion]

I used that, something like this List<User> userList = users.ToObject<List<User>>(); however it gives me an error, Error converting value .

[Parthasarathy]

Can you try users.ToObject<User[]>(). I think JSON.net treats the object as an array. Meanwhile I will try to replicate this in my machine.

[Parthasarathy]

I tried it now and it works. How are you invoking the API? Can you share the code you use for invocation?

[Robert Mansion]

see my updated question. However I'm not testing it by calling the API, I created a console project to test the deserialization.

[Robert Mansion]

which one did you try the List or as Array?

[Parthasarathy]

I tried the Array version. I did the testing using Fiddler.

[Robert Mansion]

could you try the List, it really gives me an error.

[Robert Mansion]

It would make any difference If test this in the console project that I created right? hmm, but I will try it in invoking the api.

[Parthasarathy]

No, a different client should not make any difference. I have updated the answer with the client and server code I used for testing.

[Robert Mansion]

this is funny, it's working in api invocation. :D thanks for the effort @Sarathy

[Robert Mansion]

I appreciate your help :)

[Nick]

This works fine, but it simply ignores data fields which cannot be mapped to the target class. Is there a way to get errors for that (appreciated with field name)?

[Parthasarathy]

I have not tried this yet. But there is an overload for the method ToObject<T>() which accepts an instance of JsonSerializer. You can try to create an instance of JsonSerializer and set the value of MissingMemberHandling to Error. But this will throw a JsonSerializationException as per the documentation.