Passing complex objects into a WCF Rest Service

See Denny’s post for a start, although I don’t agree with his use of GET, and passing JSON in the querystring for complex params. That seems really wrong.

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The param you use for data is the json representation of whatever your Resolution type is. For example, suppose the type and operation is defined like this on the server side:

[DataContract( Namespace = "urn:brandon.michael.hunter/ws/2010/01", 
               Name = "Resolution" )]
public class Resolution
{
    [DataMember( IsRequired = true, Name = "Name" )]
    public string Name     { get; set; } 

    [DataMember( IsRequired = true, Name = "Rank" )]
    public int Rank { get; set; }

    [DataMember( IsRequired = true, Name = "SerialNumber" )]
    public int SerialNumber { get; set; } 

    [DataMember( IsRequired = false, Name = "Id" )]
    public int Id { get; set; } 
}

[OperationContract]
[WebInvoke(Method = "PUT",
           RequestFormat=WebMessageFormat.Json,
           ResponseFormat = WebMessageFormat.Json,
           UriTemplate = "new")]
public Resolution CreateNewResolution(Resolution r)
{
    // your logic here
    r.Id = System.Guid.NewGuid();
    return r;
}

Then, in Javascript, the code you use might look like this:

var resolution = {r: { Name : "Fred", Rank : 2,  SerialNumber : 17268 }};

// convert object to JSON string  (See http://jollytoad.googlepages.com/json.js)
var objectAsJson = $.toJSON(resolution);
// result is a string:  '{"Name":"Fred","Rank":"2","SerialNumber":"17268"}'

$.ajax({
  type        : "PUT",              // must match Method in WebInvoke
  contentType : "application/json",
  url         : "Service.svc/new",  // must match UriTemplate in WebInvoke
  data        : objectAsJson, 
  dataFilter  : function (data, type) {
      // convert from "\/Date(nnnn)\/" to "new Date(nnnn)"
      return data.replace(/"\\\/(Date\([0-9-]+\))\\\/"/gi, 'new $1');
  },
  processData : false,              // do not convert outbound data to string (already done)
  success     : function(msg){ ... },
  error       : function(xhr, textStatus, errorThrown){ ... } 
 });

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Notes:

• You need to have the name of the variable (r) to be the first object in the JSON that is being passed, at least with WCF 4. When I used the previous example, it did not work until I put in the name of the variable at the beginning.
• For passing complex objects in JSON, use PUT or POST as the type (HTTP Method) of the request
• you need to convert the complex object to a JSON string. There’s a nice, tiny jquery plugin to do this. Denny provides his own implementation.
• I found that if I use processData=true, then the resulting string sent to the service is in querystring format, not in JSON. Not what I want for passing complex objects. So I set it to false. Using true would be fine for simpler non-JSON requests where you’re doing WebGet, and all the params are in the query string.
• the dataFilter allows for correct deserialization of DateTime objects
• the msg param passed to the success callback contains the returned json.
• You may want to use a URL rewriter to hide that .svc tag in the request URL
• in this case, the WCF service uses the webHttp behavior, not enableWebScript. The latter dynamically generates Javascript proxies to invoke the service, but the way you asked the question, makes it seem like you don’t want that.

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