Question

I have a WCF Ajax enabled web service that I call via jquery. It returns fine when I test it by just returning a string. As soon as I add some more functionality, the javascript error callback runs with no useful data. Just says ‘error’, readystate=0, status=0.

I can step through the service code and it returns an array of objects succesfully. The client doesn’t however.

Here’s the code.

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class WebAPI
{
    [OperationContract]
    [WebGet(ResponseFormat=WebMessageFormat.Json)]
    public Person[] GetPeople(Guid groupId)
    {
        using (SchedulerContext context = new SchedulerContext())
        {
            return context.People.Where(p=>p.Group_ID==groupId).ToArray();
        }
    }
}

And on the client:

<script type="text/javascript">
    $(document).ready(function () {
        $.ajax(
                {
                    type: "GET",
                    dataType: "json",
                    contentType: "json",
                    data: { groupId: 'ae09a080-5d7c-4e92-9a87-591574b7c4b8' },
                    url: "WebAPI.svc/GetPeople",
                    error: function (error) {
                        alert("error");
                    },
                    success: function (msg) {
                        alert(msg.d);
                    }
                }

        );
    });
</script>

UPDATE:
Inspecting it with fiddler, the http result is 504 and in the ‘raw’ response tab has the following:

HTTP/1.1 504 Fiddler - Receive Failure
Content-Type: text/html; charset=UTF-8
Connection: close
Timestamp: 13:52:46.107

[Fiddler] ReadResponse() failed: The server did not return a response for this request.

UPDATE – 2012/05/04: (btw, happy star wars day everyone!)
I figured out that the problem was in the JSON serialising. It gives a Circular Reference Exception on my entity model. Still working on a solution.

Answer 1

Can you modify your service method definition to below:

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class WebAPI
{
    [OperationContract]
    [WebGet(UriTemplate="GetPeople/{groupId}",ResponseFormat=WebMessageFormat.Json)]
    public Person[] GetPeople(Guid groupId)
    {
        using (SchedulerContext context = new SchedulerContext())
        {
            return context.People.Where(p=>p.Group_ID==groupId).ToArray();
        }
    }
}

Now perform a GET request from Fiddler with the request as below:

GET http://localhost:15006/WebAPI.svc/GetPeople/739526F1-7C58-4E3B-97D8-4870948BFE32 HTTP/1.1
Content-Type: application/json
User-Agent: localhost

Now try to perform the same from your jquery call and see how the request looks.