jQuery ASP.net Web服务消耗

Question

I have been looking on how to consume a webmethod using the $.ajax call using this code below:

$.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "WebService.asmx/HelloWorld",
            data: "{}",
            dataType: "json",
            success: function(msg) {
                alert(msg.d);
            }
        });

However when I tried to change the type from "POST" to "GET", the call didn't go through. Can someone please point out a reason why this happens?

Answer 1

By degault GET requests are disabled for ASP.Net AJAX Web services, ScottGu has an excellent blog entry on this , including how to bypass that security if that's what you're after.

Here's an example fix, by setting UseHttpGet on the ScriptMethodAttribute :

[WebMethod, ScriptMethod(UseHttpGet=true)] 
public string HelloWorld() 
{
  return "Hello World";
}

Answer 2

As Nick wrote you can use ScriptMethodAttribute or you can enable GET request processing in web.config:

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

Answer 3

have you tried checking the server side code to see where it pulls values from? it may not respond depending on the method used.

also an aside: if you are retrieving data from a web service, the logically correct method is usually GET.