C# Web Api - NUnit Testing - Newtonsoft.Json.JsonSerializationException

Question

I need to deserialize the following JSON string.

{"status":"success","data":[{"id":4,"domainTitle":"Java","isDeleted":true},{"id":5,"domainTitle":"PHP","isDeleted":true},{"id":6,"domainTitle":"Angular","isDeleted":true}]}

The test code for the same is:

[Test]
    public async Task TestGetDeletedDomainsAsync_UserDomains_StatusCodeOK()
    {
        using (var adminController = new AdminController(_adminService.Object))
        {
            //act
            var response = _adminController.GetDeletedDomainsAsync();
            var successStatus = await response.Content.ReadAsAsync<SuccessStatus>();
            var returnData = JsonConvert.DeserializeObject<List<Domain>>(successStatus.Data.ToString());
            // assert
            Assert.Multiple(() =>
            {
                Assert.That(response, Is.TypeOf<HttpResponseMessage>());
                Assert.That(returnData, Is.TypeOf<List<Domain>>());
                Assert.AreEqual(response.StatusCode, HttpStatusCode.OK);
                Assert.IsNotNull(successStatus);
                Assert.AreEqual("success", successStatus.Status);
                Assert.IsNotNull(returnData);
                //checking if same object goes to service and also if that service is called once
                _adminService.Verify(s => s.GetDeletedDomains(), Times.Once);
            });
        }
    }

But when I try using the de-serializer, it gives an exception.

Newtonsoft.Json.JsonSerializationException: Cannot deserialize the current JSON object (eg {"name":"value"}) into type 'System.Collections.Generic.List`1[IMS_NL.Models.Domain]' because the type requires a JSON array (eg [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (eg [1,2,3]) or change the deserialized type so that it is a normal .NET type (eg not a primitive type like integer, not a collection type like an array or List) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.

The line that displays the above error is --

var returnData = JsonConvert.DeserializeObject<List<Domain>>(successStatus.Data.ToString());

Help me with a solution. Thanks in advance.

Answer 1

You need to make a class which correspond your JSON string

public class Answer
{
    public string Status { get; set; }
    public List<Domain> Data { get; set; }
}

public class Domain
{
    public int Id { get; set; }
    public string DomainTitle { get; set; }
    public bool IsDeleted { get; set; }
}

Then use var returnData = JsonConvert.DeserializeObject<Answer>(successStatus.Data.ToString());

Answer 2

I think that your problem resides in the declaration of Domain class. You should define the below classes, according to the JSON you have posted:

public class Domain
{
    public int id { get; set; }
    public string domainTitle { get; set; }
    public bool isDeleted { get; set; }
}

public class Result
{
    public string status { get; set; }
    public List<Domain> data { get; set; }
}


var returnData = JsonConvert.DeserializeObject<Result>(...);

You should replace the ... with the JSON you get from that you call.

Optionally, you could rename the above classes as you think that would be more suitable.