Question

When I post my ajax data to my webservice I keep getting this error. I have tried many times and changed my code to return a json string back but it fails every time.All im trying to do is send back the data I have posted so I know it works. I have looked for answers and I have tried other alternatives but im not getting the results here is the error

{“Message”:”Invalid web service call, missing value for parameter: \u0027filters\u0027.”,”StackTrace”:” at System.Web.Script.Services.WebServiceMethodData.CallMethod(Object target, IDictionary2 parameters)\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”}

jquery:

data = [{'Name': 'Acer', 'Count': 1 }, {'Name': 'HP', 'Count': 2 }]
function getProducts(json, pageIndex, pageSize) {

    $.ajax({
        type: 'POST',
        url: '/website2/WebServices/GetProducts.asmx/GetProductsAndFilters',
        data: "{'data' : {'filters':" + JSON.stringify(json) + ", 'PageIndex' : " + pageIndex + ", 'PageSize' : " + pageSize +  "}}",
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        success: function (responseText) {
            //alert(responseText.d);
            $('.console').html(responseText.d);
        },
        error: function (xhr, status, error) {
            //var msg = JSON.parse(xhr.responseText);
            //alert(msg.Message);
            $('.console').html(xhr.responseText)
        }
    });
}
getProducts(data, "0", "2")

C#:

public class dvals
{
    public string Name { get; set; }
    public string Count { get; set; }
}

public class data
{
    public List<dvals> Filters {get;set;}
    public string PageIndex { get; set; }
    public string PageSize { get; set; }
}

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public data GetProductsAndFilters(data filters)
{
    JavaScriptSerializer js = new JavaScriptSerializer();
    //List<dvals> json = js.Deserialize<List<dvals>>(filters);
    //data json = js.Deserialize<data>(filters);
    var fname = "";
    /*
    foreach (var filter in filters)
    {
        if (filter.Name == "Acer")
        {
            fname = filter.Name;
            break;
        }

    }*/
    return filters; 
}

Answer 1

ASP.NET will handle the JSON [de]serialization for you automatically. Change your server-side method to match the type of data you’re passing in from the client-side.

edit: And as Jon pointed out, your data parameter’s property key needs to match the WebMethod’s input parameter name (this is case-sensitive even).

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public List<dvals> GetProductsAndFilters(List<dvals> dvals)
{
  // Do what you need to with "filters" here.

  return filters;
} 

Also, where is the json variable in your JSON.stringify() call defined? It looks like that should be data, given the code you’ve shown us.