Calling web service using javascript error

Question

I try to call webservice using json , when i call to web service without excepted parameters , its work , but when i'm try to send parameter , ive got an error :

This is my code:

function GetSynchronousJSONResponse(url, postData) 
{

    var xmlhttp = null;
    if (window.XMLHttpRequest)
        xmlhttp = new XMLHttpRequest();
    else if (window.ActiveXObject) {
        if (new ActiveXObject("Microsoft.XMLHTTP"))
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        else
            xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    }

    url = url + "?rnd=" + Math.random(); // to be ensure non-cached version

    xmlhttp.open("POST", url, false);
    xmlhttp.setRequestHeader("Content-Type", "application/json; charset=utf-8");
    xmlhttp.send(postData);
    var responseText = xmlhttp.responseText;
    return responseText;
}


function Test() 
{
    var result = GetSynchronousJSONResponse('http://localhost:1517/Mysite/Myservice.asmx/myProc', '{"MyParam":"' + 'test' + '"}');
    result = eval('(' + result + ')');
    alert(result.d);
}

This is the error :

System.InvalidOperationException: Request format is invalid: application/json; charset=utf-8.

at System.Web.Services.Protocols.HttpServerProtocol.ReadParameters()

at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest

What is wrong ?

Thanks in advance .

the line ` url = url + "?rnd=" + Math.random();` is unnecessary, POST requests are never cached. — Andy E
– Andy E, Commented Feb 2, 2010 at 15:01
@Andy E: POST requests are never cached by standard, and we all know some user-agents have very low regards for standards. I won't name any (the one that usually comes to mind is fortunately not plagued by this issue). — Andrew Moore
– Andrew Moore, Commented Feb 2, 2010 at 15:06
@Andrew Moore: I must say I'm not aware of any, but then again I only use Chrome and IE. Still in cases where a POST request would be cached, the timestamp could be set in the POST data or the more appropriate if-modified-since request header could be set. — Andy E
– Andy E, Commented Feb 2, 2010 at 15:33
@Andy E: The culprits usually cache using a hashed version of the URL. A few mobile browsers come to my mind. Therefore the only viable solution is a GET parameter unfortunately. — Andrew Moore
– Andrew Moore, Commented Feb 2, 2010 at 15:51
@Andrew Moore: Very well, I stand corrected and will say no more on the matter :-) — Andy E
– Andy E, Commented Feb 2, 2010 at 16:00

Rajesh Kumar · Accepted Answer · 2016-09-27 05:39:07Z

U can call web service in javascript it will return JSON :)

$.ajax({
    type: "POST",
    url: '<%=ResolveUrl("~/DesktopModules/TECH_WEBRTC/Service/Users.asmx/Getprovider")%>',
    data: JSON.stringify({id:'a'}),
            contentType: "application/json; charset=utf-8",

            dataType: "json",
            processData: false,
            success: (function (providerlist) {


                var obj = jQuery.parseJSON(providerlist.d);
                providers(obj);
            }
            ),
            error: function (data)
            {

            }
 });




namespace TECH_WEBRTC.Service
 {
/// <summary>
/// Summary description for Users
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
 [System.Web.Script.Services.ScriptService]
public class Users : System.Web.Services.WebService
{



    [WebMethod]
    //[ScriptMethod(ResponseFormat = ResponseFormat.Json)]//Specify return format.
    public string Getprovider(string id)
    {

        List<Comman1> obj = new List<Comman1>();
        JavaScriptSerializer js = new JavaScriptSerializer();

        obj.Add(new Comman1{id="1"});
            obj.Add(new Comman1{id="2"});
            obj.Add(new Comman1 { id = "2" });

            //Context.Response.Write(js.Serialize(obj.ToList()));

        return js.Serialize(obj.ToList());

    }
}

}

Its working fine:)

Andy E · Accepted Answer · 2010-02-02 15:07:45Z

From what I can tell, your application cannot accept application/json as a post data format. Use application/x-www-form-urlencoded instead and set your JSON to a request parameter that you can then access using Request.Params["key"]:

xmlhttp.open("POST", url, false); 
xmlhttp.setRequestHeader(
    "Content-Type", "application/x-www-form-urlencoded; charset=utf-8"
); 
xmlhttp.send("json="+encodeURIComponent(postData)); 
var responseText = xmlhttp.responseText; 
return responseText;

Also, as I mentioned in my comment, you can remove the following line:

url = url + "?rnd=" + Math.random(); // to be ensure non-cached version

POST requests aren't cached and it's generally bad practice to use GET parameters with POST requests.

ssvinarenko · Accepted Answer · 2011-09-20 11:49:28Z

1

I've fixed similar problem by adding these lines into server's web.config:

<handlers>
  <add name="ScriptHandlerFactory" verb="*" path="*.asmx" type="System.Web.Script.Services.ScriptHandlerFactory" />
</handlers>

Check out this page: http://msdn.microsoft.com/en-us/library/bb763183.aspx

answered Sep 20, 2011 at 11:49

ssvinarenko

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