ASP.NET webservice responds with Internal Server Error (500) to post and get requests - asp.net

Question

The webservice code is simple:
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void receiveOrder(string json) {
Context.Response.Write("ok");
}
And the jquery calling the webservice is as follows:
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: 'http://localhost:50730/GingerWeb.asmx/receiveOrder',
data: 'test', //JSON.stringify(webOrder),
dataType: "text",
success: function(data){
if(data === "ok")
orderPlaced();
}
});
And yet the chrome console reads in provocative red:
500 (Internal Server Error)

Answer 1

The problem is that ASMX web-service need to find all input parameters in the request. If at least one input parameter will be not found in the request to the server the web service failed with the status code 500 (Internal Server Error).
The reason is that you send the data in the wrong way. The name of the input parameter of the web method is json (see void receiveOrder(string json)). So the data option of the $.ajax should be in the form
data: JSON.stringify({json: webOrder})
if you use type: "POST" instead of data: JSON.stringify(webOrder) which you tried before. In the case in the body of the POST request will be json=theVlue instead of just theValue.
If you would use type: "GET" the format of data parameter should be changed to
data: {json: JSON.stringify(webOrder)}
The value of the dataType should be 'json'. After the changes the $.ajax should work.
Moreover I would recommend you to use relative paths in the url option. I mean to use '/GingerWeb.asmx/receiveOrder' instead of 'http://localhost:50730/GingerWeb.asmx/receiveOrder'. It will save you from same origin policy errors.

Answer 2

Hello Oleg: Your explanation is simple and to the point. I had a similar problem which your explanation solved. I am providing code snippet to help 'searchers' understand what I was facing and how the above helped solve. In short I am issuing a simple jquery (.ajax) from a aspx page. I have created a webservice that gets some data from backend (cache/db) and return's the same in json format.
JS CODE:
var parameters = "{'pageName':'" + sPage + "'}"
var request = $.ajax({
type: "POST",
url: "/NotificationWebService.asmx/GetNotification",
data: parameters,
contentType: "application/json; charset=utf-8",
dataType: "json"
});
ASP.NET Code Behind for Web Service
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string GetNotification(string pageName)
{
JavaScriptSerializer js = new JavaScriptSerializer();
Notification ns = NotificationCache.GetActiveNotificationForPage(pageName);
if (ns != null)
{
NotificationJSData nJSData = new NotificationJSData();
nJSData.Code = ns.Code;
nJSData.displayFreq = (short)ns.DisplayFreq;
nJSData.expiryDate = ns.ToDateStr;
return js.Serialize(nJSData);
}
return null;
}
It is ABSOLUTELY necessary to ensure that you match 'pageName' variable name specified in web service code with what is sent in your data parameter of the ajax request. I had them different and changed it to be the same, after spending hours, I finally found the right solution, thanks to this post. Also, in my case I am only passing a single "name:value" pair so I didn't even have to use some json De-serialization function to get the value, pageName above gives me only the value.