How to deserialise JSON to FHIR valueset resource in .net

I'm having trouble casting a a response from a valueset expansion to the valueset resource object in c#.

I'm currently using RestSharp, the REST call is successful, and the following outputs the expected JSON.

IRestResponse response = client.Execute(request);
var result = JsonConvert.DeserializeObject(response.Content);
Console.WriteLine(result);

I've tried

var result = JsonConvert.DeserializeObject<ValueSet>(response.Content);

But it produces a null object. I'm sure I'm making some rookie error, and perhaps should look into using the Hl7.Fhir.Rest instead of RestSharp?

Solution

So I did end up being able to deserialise the RestSharp JSON response, by creating custom ValueSet class (I just used http://json2csharp.com/ for my experiment).

However I took @Mirjam's advice, and used Hl7.Fhir.Rest instead (And ValueSet class from HL7.Fhir.Model - which contains so much more goodness than could be achieved using a custom class.

// using using Hl7.Fhir.Model;
// using Hl7.Fhir.Rest;

const string Endpoint = "https://ontoserver.csiro.au/stu3-latest";
var client = new FhirClient(Endpoint);

//uri for the value set to be searched, and text filter         
var filter = new FhirString("inr");
var vs_uri = new FhirUri("http://snomed.info/sct?fhir_vs=refset/1072351000168102");

ValueSet result = client.ExpandValueSet(vs_uri, filter);
 
//Write out the display term of the first result.
Console.WriteLine(result.Expansion.Contains.FirstOrDefault().Display);

There's a couple of other approaches, that support additional parameters...

Code available - https://gist.github.com/MattCordell/32f3c62b4e66bd1ecb17b65f2f498acb