How to access server controls from page methods?

Question

If i use a page method like this :

[System.Web.Services.WebMethod]
        public static string GetSearchResult(string searchKeyword)
        {
            ArrayList searchResultRows = new ArrayList();
            Random random = null;
            for (int resultCount = 0; resultCount < 10; resultCount++)
            {
                random = new Random(resultCount);
                searchResultRows.Add(string.Concat(searchKeyword, random.Next().ToString()));
            }
            GridView resultRepeater = new GridView();
            resultRepeater.DataSource = searchResultRows;
            resultRepeater.DataBind();

            StringBuilder stringBuilder = new StringBuilder();
            System.IO.StringWriter textWriter = new System.IO.StringWriter(stringBuilder);
            HtmlTextWriter htmlTextWriter = new HtmlTextWriter(textWriter);
            resultRepeater.RenderControl(htmlTextWriter);
            if (HttpContext.Current != null)
            {
                Page page = (Page)HttpContext.Current.Handler;
                Label lbl = (Label)page.FindControl("lbl_test");//null
                lbl.Text = searchResultRows[0].ToString();//exception
            }
            return stringBuilder.ToString();
        }

---

I want to update my existing label lbl_test but i can't access the label to set it's value ,How to access server controls from page methods ?

Answer 1

HTML

<asp:TextBox ID="txtSearch" runat="server"></asp:TextBox>
<input id="btnSearch" type="button" value="Search"
    onclick = "GetSearchResult()" />
</div>

JavaScript:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js" type="text/javascript"></script>
<script type = "text/javascript">
function GetSearchResult() {
    $.ajax({
        type: "POST",
        url: "CS.aspx/GetSearchResult",
        data: '{search: "' + $("#<%=txtSearch.ClientID%>")[0].value + '" }',
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: OnSuccess,
        failure: function(response) {
            alert(response.d);
        }
    });
}
function OnSuccess(response) {
    alert(response.d);
}
</script>