How do I serialize/deserialize .NET dictionary without key value elements?

Question

I'm trying to get my C# class to serialize to a json that complies with GP Job, for example:

 {
      "jobId" : "jb10b153b77e74a839e31af53e5d4d0d1", 
      "jobStatus" : "esriJobSucceeded", 
      "results" : {
        "output_Buffer" : {"paramUrl" : "results/output_Buffer"}, 
        "Final_wellpoints" : {"paramUrl" : "results/Final_wellpoints"}
      }, 
      "inputs" : {
        "Input_Features" : {"paramUrl" : "inputs/Input_Features"}, 
        "Distance" : {"paramUrl" : "inputs/Distance"}
      }, 
      "messages" : [
        {"type" : "esriJobMessageTypeInformative", "description" : "Submitted."}, 
        {"type" : "esriJobMessageTypeInformative", "description" : "Executing..."}, 
        {"type" : "esriJobMessageTypeInformative", "description" : "Succeeded."}
      ]
    }

But my dictionaries (results and inputs) serialize with key/value cruft:

//
{
        "jobId":"jb10b153b77e74a839e31af53e5d4d0d1", 
        "jobStatus":"esriJobSucceeded", 
        "results":[    
            {"Key":"output_Buffer",     "Value":      {"paramUrl":"results/output_Buffer"}},    
            {"Key":"Final_wellpoints",     "Value":        {"paramUrl":"results/Final_wellpoints"}}], 
        "inputs":[    
            {"Key":"Input_Features",     "Value":        {"paramUrl":"inputs/Input_Features"}},    
            {"Key":"Distance",     "Value":        {"paramUrl":"inputs/Distance"}}], 
        "messages":[    
            {"type":"esriJobMessageTypeInformative",     "description":"Submitted."},    
            {"type":"esriJobMessageTypeInformative",     "description":"Executing..."},    
            {"type":"esriJobMessageTypeInformative",     "description":"Succeeded."}
        ]
}

Update: I've commented out the WCF code and replaced with Json.NET call.

[DataContract]
public class GPJob
{
    public static string Test()
    {

        Dictionary<string,taskParam> resDict = new Dictionary<string,taskParam>();
        resDict.Add("output_Buffer",new taskParam(){ paramUrl = "results/output_Buffer"});
        resDict.Add("Final_wellpoints",new taskParam(){ paramUrl = "results/Final_wellpoints"});
        Dictionary<string,taskParam> inputDict = new Dictionary<string,taskParam>();
        inputDict.Add("Input_Features", new taskParam(){paramUrl="inputs/Input_Features"});
        inputDict.Add("Distance", new taskParam(){paramUrl="inputs/Distance"});

        GPJob job = new GPJob
        {
            jobId = "jb10b153b77e74a839e31af53e5d4d0d1",
            jobStatus = "esriJobSucceeded",
            results = resDict,
            inputs = inputDict,
            messages = new List<message>()
            {
                new message(){type="esriJobMessageTypeInformative",description = "Submitted."},
                new message(){type="esriJobMessageTypeInformative",description = "Executing..."},
                new message(){type="esriJobMessageTypeInformative",description = "Succeeded."}
            }

        };
        string json = JsonConvert.SerializeObject(job,Formatting.Indented);
        return json;
        /*
        DataContractJsonSerializer ser = new DataContractJsonSerializer(job.GetType());
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        ser.WriteObject(ms, job);
        string json = Encoding.Default.GetString(ms.ToArray());
        return json;
            */
    }

    [DataMember(Order=0)]
    public string jobId { get; set; }
    [DataMember(Order = 1)]
    public string jobStatus { get; set; }

    [DataMember(Order = 2)]
    public Dictionary<string, taskParam> results { get; set; }

    [DataMember(Order = 3)]
    public Dictionary<string, taskParam> inputs { get; set; }
    [DataMember(Order = 4)]
    public List<message> messages { get; set; }
}

[DataContract]
public class taskParam
{
    [DataMember]
    public string paramUrl { get; set; }
}
[DataContract]
public class message
{
    [DataMember(Order=0)]
    public string type { get; set; }
    [DataMember(Order = 1)]
    public string description { get; set; }
}

Here's the output:

{
  "jobId": "jb10b153b77e74a839e31af53e5d4d0d1",
  "jobStatus": "esriJobSucceeded",
  "results": {
    "output_Buffer": {
      "paramUrl": "results/output_Buffer"
    },
    "Final_wellpoints": {
      "paramUrl": "results/Final_wellpoints"
    }
  },
  "inputs": {
    "Input_Features": {
      "paramUrl": "inputs/Input_Features"
    },
    "Distance": {
      "paramUrl": "inputs/Distance"
    }
  },
  "messages": [
    {
      "type": "esriJobMessageTypeInformative",
      "description": "Submitted."
    },
    {
      "type": "esriJobMessageTypeInformative",
      "description": "Executing..."
    },
    {
      "type": "esriJobMessageTypeInformative",
      "description": "Succeeded."
    }
  ]
}

Update2 Looks like I spoke too soon, deserialization of this string fails:

string json = "{\"jobId\":\"jeabfba358b69412abeafd63e415957bf\",\"jobStatus\":\"esriJobWaiting\"," + 
                         "\"results\":[],\"inputs\":[],\"messages\":[]}";
GPJob j= JsonConvert.DeserializeObject(json, typeof(GPJob),JsonSerializerSettings) as GPJob;

I get this exception:

Cannot deserialize JSON array into type 'System.Collections.Generic.Dictionary`2[System.String,Anadarko.iMaps.JobLib.taskParam]'

It works ok when the results and inputs are not empty.

Update3:

This string deserializes:

{"jobId":"jeabfba358b69412abeafd63e415957bf","jobStatus":"esriJobWaiting","results":null,"inputs":null,"messages":null}

So here's the hack:

// hack: replace [] with null
string hackedJson = json.Replace("[]", "null");
GPJob j= JsonConvert.DeserializeObject(hackedJson, typeof(GPJob)) as GPJob;

Of course this results in a null instead of an empty dictionary. Any idea where that might cause an issue (if so, I guess I could handle that in the setters).

Answer 1

According to this, I'm going to say probably not, at least not without doing some extra work yourself. You can override the values used for Key and Value, but you're going to get the same thing as you have. You need a way to ditch representation of properties as a collection - as the underlying runtime appears to treat the dictionary as IEnumerable.

I think the short answer is to not use DataContractSerializer, and instead use an alternative method, such as Json.NET.

Answer 2

Apparently that's how the DataContractJsonSerializer is supposed to work, per this bug submittal at Microsoft Connect.

A workaround for this is referred to in the same post.