Question

I have a web method that can accept a XElement argument and I want to call it using jQuery Ajax. I can call simple methods using jQuery Ajax with simple argumnets(such as int,string,…), but I don’t know how pass to a complex type using jQuery Ajax.

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Edit 1)

I have a simple web service :

[WebMethod]
public bool MyGetPassXML(System.Xml.XmlDocument nima)
{
    try
    {
        if (nima == null )
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    catch (Exception ex)
    {
        return false;
    }
} 

For the call I’ve written this code:

var xmlFragment = ‘AB’;

$("#Button2").click(function() {
    $("#Loader").show();
    $.ajax({
        type: "POST",
        url: "WebService.asmx/MyGetPassXML",
        data: "{'nima':'" + xmlFragment + "'}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function(result) {
            $("#Loader").hide();
            alert('OK');
        }
    });
});

I’ve test it with Firefox and see request an response with FireBug but I get this error:

{“Message”:”Cannot convert object of type \u0027System.String\u0027 to type \u0027System.Xml.XmlDocument\u0027″,”StackTrace”:” at System.Web.Script.Serialization.ObjectConverter.ConvertObjectToTypeInternal(Object o, Type type, JavaScriptSerializer serializer, Boolean throwOnError, Object& convertedObject)\r\n at System.Web.Script.Serialization.ObjectConverter.ConvertObjectToTypeMain(Object o, Type type, JavaScriptSerializer serializer, Boolean throwOnError, Object& convertedObject)\r\n at System.Web.Script.Services.WebServiceMethodData.StrongTypeParameters(IDictionary2 rawParams)\r\n at System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(Object target, IDictionary2 parameters)\r\n at System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)\r\n at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)”,”ExceptionType”:”System.InvalidOperationException”}

I change System.Xml.XmlDocument to XElement but again I get this error. How can I solve this?

Answer 1

Instead of XmlDocument as the web method argument type, I would change it to a string. You can create an XmlDocument from a string by calling .LoadXml(nima).

Edit to answer the request for an example:

Let’s say you had a simple class like the following (forgive my c#):

public TestClass {

  public string Var1 { get; set; }
  public string Var2 { get; set; }

  public string void TestClass() 
  {

  }

}

And a web method like the following:

[WebMethod]
public bool MyGetPassJSON(TestClass nima)
{
  // do something
} 

And your javascript / jquery could look like the following:

   $.ajax({
        type: "POST",
        url: "WebService.asmx/MyGetPassJSON",
        data: "{nima: {Var1:'something',Var2:'something else'}}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function(result) {
            $("#Loader").hide();
            alert('OK');
        }
    });

In your case, you could have:

"cities": ["A", "B","C","D"]

This is a very simple example, but much more complex parameters are possible. You can also build up your json as a proper javascript object and use JSON.stringify to send it to your web method.