accessing the parameters of a JSON call in the web method-Collection of common programming errors

2 years ago
admin
2 minutes

I have the following JSON call, the data I’m passing seems to be getting stringify’ed properly from what i’m looking at, however, I don’t seem to have the right syntax to process the parameter in the public web method.

Here is the JSON call:

 

  var qs = new Querystring();

  var v1 = qs.get("TorVName");

  var jsonData = JSON.stringify(v1);  

        $().ready(function() {
            $.ajax({
                type: "POST",
                url: "Default.aspx/GetColumns",
                data: jsonData,
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function(msg) {
       var optString = 'Select Column';
        $.each(msg.d, function(index, item) {
        optString += '' + item + '';
        });
        $('select[name^=DDLColumns]').html(optString);
                },
                error: function() {
                    alert("Failed to load columns");
                }
            });
        });

and here is the cooresponding web method:

    [WebMethod]
    public static ArrayList GetColumns(string TorVName)
    {
        String cnstr = "myconnect string";
        string Sql = String.Empty;
        ArrayList arlist = new ArrayList();
        SqlDataReader rdr = null;
        SqlCommand cmd = null;
        DataSet dset;
        SqlConnection cn = new SqlConnection(cnstr);
        cn.Open();
        dset = new DataSet("ds");
        dset.Clear();

etc etc…

I have a hard time deciding how to debug a web method since I can only see the client side actions in firebug.

any help on how to recieve and process the parameter in the web method would be most appreciated.

Thanks Deano

  1. Your data needs to be in name/value pair format, like this:

     var jsonData = JSON.stringify({ TorVName: qs.get("TorVName") });

    The web method is looking for the property named TorVName, so you need a name/value pair with this for your JSON request, not just the string. In the above code the TorVName: is because that’s what the parameter is named in the web method.

  2. as others have stated, you need ot have a json object with a parameter of torVName since htat is what your web method is looking for. an easy way to do this is var data={};//create new object data[‘torVName’]=actual datta’; then in your ajax call you can just say data:JSON.stringify(data)

  3. maybe you guys should read this before suggesting the stringify stuff in IE8:

    JSON returns ‘undefined’ when stringifying an object that was created in a different window See test case at http://kinsey.no/examples/ie8_json_bug/

Originally posted 2013-11-10 00:11:47.