I am learing using jquery ajax to hander the JSON..i writre a demo code. HTMLCODE

$(function () {
            $("#add").click(function () {
                var json = '{ "str":[{"Role_ID":"2","Customer_ID":"155","Brands":"Chloe;","Country_ID":"96;"}]}';
                $.ajax({

                    url: "func.aspx/GetJson",
                    type: "POST",
                    contentType: "application/json",
                    dataType: 'json',
                    data: json, 

                    success: function (result) {
                        alert(result);
                    },
                    error: function () {
                        alert("error");
                    }
                });
            });
        });

 <div>
       <input type="button" value="add" id="add" />
    </div>

i got a input and bind a script function to it, now the proble is comeing.. my C# functiong like that.

[WebMethod]
        public static string GetJson(object str)
        {
            return str.ToString();//good for work


        }
        [Serializable]
        public class TestClass
        {
            public TestClass()
            {
            }

            public TestClass(string role_id, string customer_id, string brands, string countryid)
            {
                this.Role_ID = role_id;
                this.Customer_ID = customer_id;
                this.Brands = brands;
                this.Country_ID = countryid;
            }

            public string Role_ID { get; set; }
            public string Customer_ID { get; set; }
            public string Brands { get; set; }
            public string Country_ID { get; set; }
        }

when i user public static string GetJson(object str) everything is so good.~~ no error at all but . when i try to use my own class TestClass. firebug tell me that "Type 'TestClass' is not supported for deserialization of an array." .any body can give me help:XD