andy wilson andy wilson - 6 months ago 214
JSON Question

C# Json formatted response

I know I need a formatted

Newtonsoft Json
response but I don't know how to do it and I can't seem to find a tutorial or any sort of documentation that could help me out.

This is the code I have right now.
dtb is the response from the database that I need to return in a formatted
Newtonsoft Json

return Json(dtb);

This doesn't work and I'm getting an error when I try and run the next lot of code which is

Newtonsoft.Json.JsonConvert.DeserializeObject<Dictionary<string, string>>((Newtonsoft.Json.Linq.JObject.Parse(response)["d"]).ToString());
UserModel m = (UserModel)JsonConvert.DeserializeObject<UserModel>(response);
if (m.Username == context.UserName && m.PasswordHash == myHash)

I'm not sure why it breaks at the first line of this saying error

+ $exception {"Error reading JObject from JsonReader. Current JsonReader item is not an object: StartArray. Path '', line 1, position 1."} Newtonsoft.Json.JsonReaderException

error edit 1:

Newtonsoft.Json.JsonSerializationException: 'Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'AuthorizationServer.api.Models.UserModel' 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.

My code now looks like this

dynamic res = JsonConvert.DeserializeObject<Dictionary<string, string>>((Newtonsoft.Json.Linq.JToken.Parse(response)[0]).ToString());
UserModel m = (UserModel)JsonConvert.DeserializeObject<UserModel>(res);
if (m.Username == context.UserName && m.PasswordHash == myHash)

But it gives me an error at that the
UserModel m = (UserModel)JsonConvert.DeserializeObject<UserModel>(res);

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException occurred
Message=The best overloaded method match for 'Newtonsoft.Json.JsonConvert.DeserializeObject<AuthorizationServer.api.Models.UserModel>(string)' has some invalid arguments
at AuthorizationServer.api.Providers.CustomOAuthProvider.GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context) in C:\Users\wilsona\Documents\Visual Studio 2017\Projects\JsonWebTokensWebApi\AuthorizationServer.api\Providers\CustomOAuthProvider.cs:line 66
at Microsoft.Owin.Security.OAuth.OAuthAuthorizationServerHandler.<InvokeTokenEndpointResourceOwnerPasswordCredentialsGrantAsync>d__3f.MoveNext()

user model class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace AuthorizationServer.api.Models
public class UserModel

public string Username { get; set; }
public string PasswordHash { get; set; }
public int UserID { get; set; }
public string Roles { get; set; }

public UserModel(string Username, string PasswordHash, int UserID, string Roles)
this.Username = Username;
this.PasswordHash = PasswordHash;
this.UserID = UserID;
this.Roles = Roles;


json return


Which then gets passed through
dynamic res = JsonConvert.DeserializeObject<Dictionary<string, string>>((Newtonsoft.Json.Linq.JToken.Parse(response)[0]).ToString());

Which works then breaks when it hits
UserModel m = (UserModel)JsonConvert.DeserializeObject<UserModel>(res);

with this error
Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: 'The best overloaded method match for 'Newtonsoft.Json.JsonConvert.DeserializeObject<AuthorizationServer.api.Models.UserModel>(string)' has some invalid arguments'

Answer Source

The problem is that the Json is sent as array. You have to deserialize it to an Array.

This code works for me.

var jToken = JToken.Parse(response);
var users = jToken.ToObject<List<UserModel>>(); //Converts the Json to a List<Usermodel>
var user = users[0];
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