MvvmCross: Deserilization Error for JSON - json

Question

I'm trying to create a simple application through Lesson 6 in N+1 Days of MvvmCross application sample. But its failed in SimpleRestService while converting json Data serialization.
private T Deserialize<T>(string responseBody)
{ // Error is here for deserilizing
var toReturn = _jsonConverter.DeserializeObject<T>(responseBody);
return toReturn;
}
My Json data through Browser:
[{"Desc":"All","Id":"0"},{"Desc":"Assigned","Id":"2"},{"Desc":"In Progress","Id":"3"},{"Desc":"Resolved","Id":"4"},{"Desc":"Closed","Id":"5"},{"Desc":"Hold","Id":"6"},{"Desc":"低","Id":"8"},{"Desc":"Waiting Approval","Id":"9"},{"Desc":"Cancelled","Id":"10"},{"Desc":"Not Resolved","Id":"8"}]
My Json data in application at responsebody:
[{\"Desc\":\"All\",\"Id\":\"0\"},{\"Desc\":\"Assigned\",\"Id\":\"2\"},{\"Desc\":\"In Progress\",\"Id\":\"3\"},{\"Desc\":\"Resolved\",\"Id\":\"4\"},{\"Desc\":\"Closed\",\"Id\":\"5\"},{\"Desc\":\"Hold\",\"Id\":\"6\"},{\"Desc\":\"低\",\"Id\":\"8\"},{\"Desc\":\"Waiting Approval\",\"Id\":\"9\"},{\"Desc\":\"Cancelled\",\"Id\":\"10\"},{\"Desc\":\"Not Resolved\",\"Id\":\"8\"}]
Error Message shows as :
{Newtonsoft.Json.JsonSerializationException: Cannot deserialize JSON array (i.e. [1,2,3]) into type 'Book.Core.Services.BookSearchResult'.
The deserialized type must be an array or implement a collection interface like IEnumerable, ICollection or IList.
To force JSON arrays to deserialize add the JsonArrayAttribute to the type. Path '', line 1, position 1.
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureArrayContract (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract) [0x00000] in :0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateList (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, System.Object existingValue, System.String reference) [0x00000] in :0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, System.Object existingValue) [0x00000] in :0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueNonProperty (Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.JsonConverter converter, Newtonsoft.Json.Serialization.JsonContainerContract containerContract) [0x00000] in :0
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in :0
at Newtonsoft.Json.JsonSerializer.DeserializeInternal (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in :0
at Newtonsoft.Json.JsonSerializer.Deserialize (Newtonsoft.Json.JsonReader reader, System.Type objectType) [0x00000] in :0 etc.. }
My Code part:
Class Declaration:
public class BookSearchItem
{
public string Desc { get; set; }
public string Id { get; set; }
}
public class BookSearchResult
{
public List<BookSearchItem> items { get; set; }
}
Binding Declaration:
public void StartSearchAsync(string whatFor, Action<BookSearchResult> success, Action<Exception> error)
{
string address = string.Format("http://192.168.0.76/eFACiLiTYPhone/MobileService/WinPhoneWCFService.svc/callstatustesting");
_simpleRestService.MakeRequest<BookSearchResult>(address,"GET", success, error);
}
Simple Rest Service For Common:
public class SimpleRestService :ISimpleRestService
{
private readonly IMvxJsonConverter _jsonConverter;
public SimpleRestService(IMvxJsonConverter jsonConverter)
{
_jsonConverter = jsonConverter;
}
public void MakeRequest<T>(string requestUrl, string verb, Action<T> successAction, Action<Exception> errorAction)
{
var request = (HttpWebRequest)WebRequest.Create(requestUrl);
request.Method = verb;
request.Accept = "application/json";
MakeRequest(
request,
(response) =>
{
if (successAction != null)
{
T toReturn;
try
{
toReturn = Deserialize<T>(response);
}
catch (Exception ex)
{
errorAction(ex);
return;
}
successAction(toReturn);
}
},
(error) =>
{
if (errorAction != null)
{
errorAction(error);
}
}
);
}
private void MakeRequest(HttpWebRequest request, Action<string> successAction, Action<Exception> errorAction)
{
request.BeginGetResponse(token =>
{
try
{
using (var response = request.EndGetResponse(token))
{
using (var stream = response.GetResponseStream())
{
var reader = new StreamReader(stream);
successAction(reader.ReadToEnd());
}
}
}
catch (WebException ex)
{
Mvx.Error("ERROR: '{0}' when making {1} request to {2}", ex.Message, request.Method, request.RequestUri.AbsoluteUri);
errorAction(ex);
}
}, null);
}
private T Deserialize<T>(string responseBody)
{
var toReturn = _jsonConverter.DeserializeObject<T>(responseBody);
return toReturn;
}
}

Answer 1

You have to use the correct T for your Json call - you can't simply use BookSearchResult for all Json calls.
You can use tools like http://json2csharp.com/ to generate the CSharp classes for you - e.g.
public class RootObject
{
public string Desc { get; set; }
public string Id { get; set; }
}
which you can then use as:
var myItems = service.Deserialize<List<RootObject>>(jsonText);