ajax client-server communication

Question

I asked a question previously on this site about ajax client-server communication.

I got a lot of help. but still cant figure it out, so re-asking the question.

I m trying to send the value stored in the variable 'mem_ID' from my javascript page...Default.aspx to my server side - Default.aspx.cs page.

Javascript:-

<asp:Button ID="Button6" runat="server" BackColor="Silver" 
            onclientclick="store_memID()" style="margin-left: 20px" Text="Submit" 
            Width="102px" Font-Bold="True" Height="28px" />


<script type = "text/javascript" src ="http://code.jquery.com/jquery-1.9.0.min.js"> </script>


 <script type = "text/javascript"> 

        // Function to caputure client-input- Member_ID.
        function store_memID() {

            // 'TextBox3' is the server side ID. To get the client side ID we do the following:-
            mem_ID = document.getElementById('<%=TextBox3.ClientID%>').value;

            //return confirm('TimeLine is displayed for: ' + mem_ID);

            ajax();
        }


        function ajax(){
            $.ajax({
                url: 'Default.aspx/MyMethod',
                type: 'POST',
                contentType: 'application/json; charset=utf-8',
                data: JSON.stringify({ memID: mem_ID }),
                success: function (result) {
                alert(result.d);
                }
            });

        }

        </script>

Server side:-

    public partial class _Default : System.Web.UI.Page
    {


        protected void Page_Load(object sender, EventArgs e)
        {

        }


        // Defining a page method. 
        [WebMethod]
        public static string MyMethod(string mem_ID)
        {
            return string.Format("Thanks for calling me with id: " + mem_ID);



        }
` more code here`....

However, I still don't get any reply in return from the server. I am expecting the return "Thanks for calling me with ID: ..... " from the server side. Any ideas?

I added a breakpoint in MyMethod, on the response line, on the server side, and there was no hit. so I am assuming that this line is not even being traversed.

I m new to Asp.net and Ajax. and need help on this topic.

Answer 1

Normally I create an Ajax.aspx file that handle most of the client-server ajax interaction the same way it's done in the example below. Then this page loads specific controls. I sometimes add a function parameter to the ajax request to access specific methods in the controls or directly on the Ajax.aspx page.

Example:
Simple ASP.net ajax framework

Answer 2

<form id="form1" runat="server">
    <div>
    <asp:Button ID="Button6" runat="server" BackColor="Silver" 
            onclientclick="store_memID()" style="margin-left: 20px" Text="Submit" 
            Width="102px" Font-Bold="True" Height="28px" /> 
<script type = "text/javascript" src ="http://code.jquery.com/jquery-1.9.0.min.js"> </script>
 <script type = "text/javascript">

     // Function to caputure client-input- Member_ID.
     function store_memID() {
         var mem_ID;
         // 'TextBox3' is the server side ID. To get the client side ID we do the following:-
         mem_ID = document.getElementById('<%=TextBox3.ClientID%>').value;

         //return confirm('TimeLine is displayed for: ' + mem_ID);

         ajax(mem_ID);
     }
     function ajax(mem_ID) {
         alert(mem_ID);
         $.ajax({
             url: 'Default.aspx/MyMethod',
             type: 'POST',
             contentType: 'application/json; charset=utf-8',
             data: JSON.stringify({ memID: mem_ID }),
             success: function (result) {
                 alert(result.d);
             }
         });
     }
        </script>
    <asp:TextBox id="TextBox3" runat="server"></asp:TextBox>
    </div>
    </form>
In Your Code Behind

[WebMethod]
        public static string MyMethod(string memID)
        {
            return string.Format("Thanks for calling me with id: " + memID); 
        }

The method u have done all was right execpt,
The data passing from ajax should match the string Element declared in the Web-method.

Answer 3

Here's a full example I wrote for you to get started:

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Web.Services" %>
<script type="text/c#" runat="server">
    [WebMethod]
    public static string MyMethod(string memId)
    {
        return string.Format("Thanks for calling me with id: " + memId);
    }
</script>
<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <asp:Button ID="MyButton" runat="server" Text="Submit" />
        <asp:TextBox ID="MyTextBox" runat="server" />
    </form>
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
    <script type="text/javascript">
        $('#<%= MyButton.ClientID %>').click(function () {
            var memId = $('#<%= MyTextBox.ClientID %>').val();
            $.ajax({
                url: '<%= ResolveUrl("~/Default.aspx/MyMethod") %>',
                type: 'POST',
                contentType: 'application/json; charset=utf-8',
                data: JSON.stringify({ memId: memId }),
                success: function (result) {
                    alert(result.d);
                }
            });
            return false;
        });
    </script>
</body>
</html>

For the purpose of the demonstration it's a self contained WebForm but you could of course separate the code behind from the markup.

Answer 4

You are passing the value as a JSON Object, its important to specified the dataType for the request and specified the returning format from the server.

function ajax(){
            $.ajax({
                url: 'default.aspx/MyMethod',
                type: 'POST',
                dataType: "json",
                contentType: 'application/json; charset=utf-8',
                data: JSON.stringify({ memID: mem_ID }),
                success: function (result) {
                alert(result.d);
                }
            });
        }


// Defining a page method. 
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public static string MyMethod(string mem_ID)
 {
            return string.Format("Thanks for calling me with id: " + mem_ID);
 }

Then you need to add a ScriptManager and UpdatePanel to Triggers the Ajax Call. The ScriptManager provides the funcionality to call WebMethods from Aspx pages. Use this with the above code i provided.

<head runat="server">
    <title></title>
    <script type="text/javascript" src="http://code.jquery.com/jquery-1.9.0.min.js"/>
</head>
<body>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>

         <asp:Button ID="Button6" runat="server" BackColor="Silver" OnClientClick="store_memID()"
        Style="margin-left: 20px" Text="Submit" Width="102px" Font-Bold="True" Height="28px" />

         <asp:TextBox ID="TextBox3" runat="server">Testing</asp:TextBox>
    </ContentTemplate>
</asp:UpdatePanel>

</form>
</body>