Question

I’m trying create a ASMX webservice that can perform a HTTP GET request. I have the following simple snippet of code to illustrate what I’ve already done.

using System.Web.Script.Services;
...

[WebMethod]
[ScriptMethod(UseHttpGet = true)]
public string HelloWorld(HttpContext context)
{
 return context.Request.Params.Get("userId").ToString();
}

In addition to this, I’ve also added the following nodes in my Web.config file

<webServices>
  <protocols>
    <add name="HttpGet"/>
    <add name="HttpPost"/>
  </protocols>
</webServices>

The problem that I’m facing is that I’m constantly getting the dreaded “System.Web.HttpContext cannot be serialized because it does not have a parameterless constructor” error message whenever I try to debug this webservice. I have no idea what the problem is, and I would really appreciate any assistance that is offered to get me out of this quandary. I realize that HTTP GET requests are supposed to be very simple, but I’m really uncertain of what the cause of my frustrations are.

Answer 1

I think you want

[WebMethod]
[ScriptMethod(UseHttpGet = true)]
public string HelloWorld(int userId)
{
    return userId.ToString();
}

You can specify parameters in the function signature and you can access the HttpContext as Context (a property on the base class WebService) if you need it.