Deserialize JSON to Array or List with HTTPClient ReadAsAsync using NET 4 0 Task pattern

Question

I m trying to deserialize the JSON returned from http   api usa gov jobs search json query nursing jobs using the  NET 4 0 Task pattern   It returns this JSON   Load JSON data    http   jsonviewer stack hu                id    usajobs 353400300        position title    Nurse        organization name    Indian Health Service        rate interval code    PA        minimum   42492       maximum   61171       start date    2013-10-01        end date    2014-09-30        locations            Gallup  NM              url    https   www usajobs gov GetJob ViewDetails 353400300                id    usajobs 359509200        position title    Nurse        organization name    Indian Health Service        rate interval code    PA        minimum   42913       maximum   61775       start date    2014-01-16        end date    2014-12-31        locations            Gallup  NM              url    https   www usajobs gov GetJob ViewDetails 359509200                 Index Action     public class HomeController   Controller         public ActionResult Index               Jobs model   null        var client   new HttpClient          var task   client GetAsync  http   api usa gov jobs search json query nursing jobs            ContinueWith  taskwithresponse    gt                      var response   taskwithresponse Result            var jsonTask   response Content ReadAsAsync lt Jobs gt               jsonTask Wait              model   jsonTask Result                    task Wait                       Jobs and Job class      JsonArray    public class Jobs   public List lt Job gt  JSON       public class Job          JsonProperty  organization name        public string Organization   get  set         JsonProperty  position title        public string Title   get  set          When I set a breakpoint on jsonTask Wait    and examine jsonTask the status is Faulted   The InnerException is  Type ProjectName Jobs is not a collection    I started with the Jobs type without the JsonArray attribute and Jobs as an array  Job    and got this error     public class Jobs   public Job   JSON                 InnerException    Cannot deserialize the current JSON array  e g   1 2 3   into type  ProjectName Models Jobs  because the type requires a JSON object  e g     name     value     to deserialize correctly  r n     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 lt T gt  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  r n Path     line 1  position 1     System Exception  Newtonsoft Json JsonSerializationException    How would I process this site s JSON with the  NET 4 0 Task pattern   I would like to get this working before moving onto the await async pattern in  NET 4 5   ANSWER UPDATE   Here s an example using the  NET 4 5 async await pattern with brumScouse s answer    public async Task lt ActionResult gt Index          List lt Job gt  model   null      var client   newHttpClient             NET 4 5 async await pattern     var task   await client GetAsync http   api usa gov jobs search json query nursing jobs       var jsonString   await task Content ReadAsStringAsync        model   JsonConvert DeserializeObject lt List lt Job gt  gt  jsonString       returnView model        You will need to bring in the System Threading Tasks namespace  Note  there is no  ReadAsString method available on  Content which is why I used the  ReadAsStringAsync method

User · Accepted Answer

Instead of handcranking your models try using something like the Json2csharp.com website. Paste In an example JSON response, the fuller the better and then pull in the resultant generated classes. This, at least, takes away some moving parts, will get you the shape of the JSON in csharp giving the serialiser an easier time and you shouldnt have to add attributes.

Just get it working and then make amendments to your class names, to conform to your naming conventions, and add in attributes later.

EDIT: Ok after a little messing around I have successfully deserialised the result into a List of Job (I used Json2csharp.com to create the class for me)

public class Job
{
        public string id { get; set; }
        public string position_title { get; set; }
        public string organization_name { get; set; }
        public string rate_interval_code { get; set; }
        public int minimum { get; set; }
        public int maximum { get; set; }
        public string start_date { get; set; }
        public string end_date { get; set; }
        public List<string> locations { get; set; }
        public string url { get; set; }
}

And an edit to your code:

        List<Job> model = null;
        var client = new HttpClient();
        var task = client.GetAsync("http://api.usa.gov/jobs/search.json?query=nursing+jobs")
          .ContinueWith((taskwithresponse) =>
          {
              var response = taskwithresponse.Result;
              var jsonString = response.Content.ReadAsStringAsync();
              jsonString.Wait();
              model = JsonConvert.DeserializeObject<List<Job>>(jsonString.Result);

          });
        task.Wait();

This means you can get rid of your containing object. Its worth noting that this isn't a Task related issue but rather a deserialisation issue.

EDIT 2:

There is a way to take a JSON object and generate classes in Visual Studio. Simply copy the JSON of choice and then Edit> Paste Special > Paste JSON as Classes. A whole page is devoted to this here:

http://blog.codeinside.eu/2014/09/08/Visual-Studio-2013-Paste-Special-JSON-And-Xml/

User · Answer

var response   taskwithresponse Result            var jsonString   response ReadAsAsync lt List lt Job gt  gt    Result

User · Answer

The return type depends on the server  sometimes the response is indeed a JSON array but sent as text plain  Setting the accept headers in the request should get the correct type   client DefaultRequestHeaders Accept Add new MediaTypeWithQualityHeaderValue  application json        which can then be serialized to a JSON list or array  Thanks for the comment from  svick which made me curious that it should work   The Exception I got without configuring the accept headers was System Net Http UnsupportedMediaTypeException   Following code is cleaner and should work  untested  but works in my case        var client   new HttpClient        client DefaultRequestHeaders Accept Add new MediaTypeWithQualityHeaderValue  application json         var response   await client GetAsync  http   api usa gov jobs search json query nursing jobs        var model   await response Content ReadAsAsync lt List lt Job gt  gt

[c#] Deserialize JSON to Array or List with HTTPClient .ReadAsAsync using .NET 4.0 Task pattern

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