Page method not called

I set up a page method and am trying to call it through jQuery. Sometimes I get to the success function and sometimes to the error function, seems random to me. In any case, the response contains the entire page mark-up.

I tried using both $.ajax and ScriptManager with same results. I also tried the idea here: Call ASP.NET PageMethod/WebMethod with jQuery - returns whole page and nothing.

Here is the JavaScript code:

$(document).ready(function() {
    $(".tree").dynatree({
        onActivate: function(node) {
            $('#title').val(node.data.title);
            $.ajax({
                type: "POST",
                url: window.location.href + "/GetData",
                data: "{'ID':22}",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function(response) { alert(response); },
                error: function() { alert('Error!'); }
            });
        }
    });
});

And here is the c# code:

[WebMet开发者_StackOverflowhod]
public static string GetData(string ID)
{
    if (string.IsNullOrEmpty(ID))
        throw new Exception("No ID passed!");
    return "Test";
}

Edit: Well I got it working. I changed the parameter type from int to string and now the method is called. I can just do int.Parse later, but why does this even happen?

---

What's happening is that setting data to {} in the jQuery call is the JSON equivalent of setting it to NULL. In that case, there is no webmethod that accepts null and the call fails.

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I'm doing something very similar in my current app and the only difference I can see is that i have the following extra option in my ajax call :

beforeSend: function(xhr) { xhr.setRequestHeader("Content-type", "application/json; charset=utf-8"); }

Hope that helps...