How to parse this 3rd party JSON service using .NET?

Question

I am trying to read a web service api via my .NET desktop application. I have tried the following, but nothing is being populated. Via Fiddler, if I click on the [Raw] tab, the response looks like:

HTTP/1.1 200 OK 
Date: Fri, 01 Aug 2014 21:49:48 GMT 
Server: Apache
X-Powered-By: PHP/5.3.3 
Connection: close 
Content-Length: 125478
Access-Control-Allow-Origin: * 
Content-Type: application/json
Content-Language: en

{"request":{"command":"project","project_id":"XYZ123"},"project":[{"project_id":"XYZ123","name":"Project Financials","description":"Sales","state":"CA","dept":"Finance","modified":"2014-08-01","data":[["20140801", 112423],["20140731", 689944],["20140730", 9855], ["20140729", 13118], ["20140728", 9448],
... more data ...
["20140318", 1546], ["20140317", 5467], ["20140316", 19578], ["20140315", 90158]]}]}

I would like to capture the data points, i.e. the "data" from the above JSON segment. For this I have a simple class as follows:

public class DailySales
{
    public datetime Date { get; set; }
    public int UnitsSold { get; set; }
}

And here is my web service code:

private void GetSales()
{
      var webClient = new WebClient();
      webClient.OpenReadCompleted += webClient_OpenReadCompleted;
      webClient.OpenReadAsync(new Uri("http://3rdPartySite.com"));
}

void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
      var json = new DataContractJsonSerializer(typeof(List<DailySales>));
      var data = (List<DailySales>)json.ReadObject(e.Result); // returns null  
}

Any tips on what I am missing would be appreciated.

Answer 1

Well, your json isn't deserializing because your class model doesn't match it at all.

First, create a proper model (this was generated using json2csharp):

public class Request
{
    public string command { get; set; }
    public string project_id { get; set; }
}

public class Project
{
    public string project_id { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public string state { get; set; }
    public string dept { get; set; }
    public string modified { get; set; }
    public List<List<object>> data { get; set; }
}

public class RootObject
{
    public Request request { get; set; }
    public List<Project> project { get; set; }
}

Note data is generated as a List<List<object>> as it doesn't recognize a common pattern. You can change that to a class containing an int and a DateTime object, but you'll have to convert that int in your JSON to a DateTime object manually.

On the webrequest side, you can use HttpClient along with the new async-await feature in .NET 4.5, along with Json.NET:

public async Task RequestAndDeserializeJson()
{
    var httpClient = new HttpClient();
    var json = await httpClient.GetAsStringAsync("http://3rdPartySite.com");
    RootObject obj = JsonConvert.Deserialize<RootObject>(json);
}

If you only want to extract the data points, you can use JObject.Parse in the Json.NET api:

var jobject = JObject.Parse(json);

// Extract data points only
var dataPoints = jobject["project"]["data"];