Paul Knopf Paul Knopf - 6 months ago 147
JSON Question

Returning raw json (string) in wcf

I want to build my own JSON, and have the service return a string, here is the code

[OperationContract]
[WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.Bare, ResponseFormat = WebMessageFormat.Json)]
public string GetCurrentCart()
{
//Code ommited
string jsonClient = null;
var j = new { Content = response.Content, Display=response.Display, SubTotal=response.SubTotal};
var s = new JavaScriptSerializer();
jsonClient = s.Serialize(j);
return jsonClient;
}


The response I am getting contains the \" used to create "'s in strings in c#.

The following is the response.

"{\"Content\":\"\\r\\n\\u003cdiv\\u003e\\r\\n\\u003cinput type=\\\"hidden\\\" name=\\\"__VIEWSTATE\\\" id=\\\"__VIEWSTATE\\\" value=\\\"\/wEPDwUBMA9kFgJmD2QWAmYPZBYGAgMPFgIeBFRleHQFKFlvdSBoYXZlIG5vIGl0ZW1zIGluIHlvdXIgc2hvcHBpbmcgY2FydC5kAgUPFgIeB1Zpc2libGVoZAIHDxQrAAIPFgIfAWhkZGQYAQUMY3RsMDEkbHZDYXJ0D2dkoWijqBUJaUxmDgFrkGdWUM0mLpgQmTOe8R8hc8bZco4=\\\" \/\\u003e\\r\\n\\u003c\/div\\u003e\\r\\n\\r\\n\\u003cdiv class=\\\"block block-shoppingcart\\\"\\u003e\\r\\n \\u003cdiv class=\\\"title\\\"\\u003e\\r\\n \\u003cspan\\u003eShopping Cart\\u003c\/span\\u003e\\r\\n \\u003c\/div\\u003e\\r\\n \\u003cdiv class=\\\"clear\\\"\\u003e\\r\\n \\u003c\/div\\u003e\\r\\n \\u003cdiv class=\\\"listbox\\\"\\u003e\\r\\n You have no items in your shopping cart.\\r\\n \\r\\n \\r\\n \\u003c\/div\\u003e\\r\\n\\u003c\/div\\u003e\\r\\n\",\"Display\":\"You have no items in your shopping cart.\",\"SubTotal\":null}"


The values are being correctly encoded, but the json itself is not properly formatted. These \'s cause it to go out of wack.

How do I return a string without the \'s in front of the "'s?

Answer

Currently your web method return a String together with ResponseFormat = WebMessageFormat.Json. It follow to the JSON encoding of the string. Corresponds to www.json.org all double quotes in the string will be escaped using backslash. So you have currently double JSON encoding.

The easiest way to return any kind of data is to change the output type of GetCurrentCart() web method to Stream or Message (from System.ServiceModel.Channels) instead of String.
See http://blogs.msdn.com/b/carlosfigueira/archive/2008/04/17/wcf-raw-programming-model-web.aspx, http://msdn.microsoft.com/en-us/library/ms789010.aspx and http://msdn.microsoft.com/en-us/library/cc681221(VS.90).aspx for code examples.

Because you don't wrote in your question which version of .NET you use, I suggest you to use an universal and the easiest way:

public Stream GetCurrentCart()
{
    //Code ommited
    var j = new { Content = response.Content, Display=response.Display,
                  SubTotal=response.SubTotal};
    var s = new JavaScriptSerializer();
    string jsonClient = s.Serialize(j);
    WebOperationContext.Current.OutgoingResponse.ContentType =
        "application/json; charset=utf-8";
    return new MemoryStream(Encoding.UTF8.GetBytes(jsonClient));
}