How to fire click event of linkbutton inside DataList control in ASP.NET 4.0

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event

datalist

I have a Datalist control which populates a list of categories as a linkbuttons. Clicking specific category I would like to populate associated subcategories.

But, not sure how to fire click event of linkbutton inside datalist control.

I tried to use CommandArgument and CommandName properties, but event is still not firing.

Below is the sample code..

 <asp:DataList ID="DataList1" runat="server" DataKeyField="CatID">
  <ItemTemplate>
    <li>
       <asp:LinkButton ID="LinkButton1" runat="server" CommandName="ShowSubCats" CommandArgument='<%# Eval("CatID") %>' OnClick="populateSubCats"><%# Eval("Category") %>   </asp:LinkButton>
   </li>
   </ItemTemplate>
</asp:DataList>

//CODE BEHIND CS FILE CODE

protected void populateSubCats(object sender, EventArgs e)
    {
        // Code for populating Sub Categories GOES HERE...!
    }

----------------------------------------------- UPDATE -----------------------------------------
------------------------------------------------------------------------------------------------

Hi I resolved problem myself, but having another problem, code behind not able find CHILD Datalist control(for subcategories) contained into PARENT datalist control

I'am getting ERROR: <b>The name 'DataList2' does not exist in the current context</b>

Below is the SAMPLE CODE


// ----------------- subMenus.aspx ----------------------

<ul>
            <asp:datalist id="DataList1" runat="server" datakeyfield="CatID" xmlns:asp="#unknown">
                <itemtemplate>
                    <li>
                        <asp:linkbutton id="LinkButton1" runat="server" commandname="Display" oncommand="ImageButton_Command" commandargument="&lt;%# Eval("CatID") %&gt;"><![CDATA[<%# Eval("Category") %>]]></asp:linkbutton>
                    </li>
                    <ul>
                        <asp:datalist id="DataList2" runat="server">
                            <itemtemplate>
                                <li>
                                    <asp:linkbutton id="LinkButton2" runat="server" commandname="Display"><![CDATA[<%# Eval("SubCategory") %>]]></asp:linkbutton>
                                </li>
                            </itemtemplate>
                        </asp:datalist>
                    </ul>
                </itemtemplate>
            </asp:datalist>
        </ul>

//-------------- subMenus.aspx.cs ------------------------

protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            populateCatefories();
        }
    }

    protected void populateCatefories()
    {
        SqlConnection conn = new SqlConnection(clsConnection.connectionString());
        SqlCommand cmd = new SqlCommand();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "GetAllCategories";
        cmd.Connection = conn;
        try
        {
            conn.Open();
            DataList1.DataSource = cmd.ExecuteReader();
            DataList1.DataKeyField = "CatID";
            DataList1.DataBind();
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
        finally
        {
            conn.Close();
            cmd.Dispose();
        }
    }

    protected void ImageButton_Command(object sender, CommandEventArgs e)
    {
        if (e.CommandName == "Display")
        {
            getSubCategories(Convert.ToInt32(e.CommandArgument));
        }
    }
    protected void getSubCategories(int subCatID)
    {
        SqlConnection conn = new SqlConnection(clsConnection.connectionString());
        SqlCommand cmd = new SqlCommand();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "getsubCategories";
        cmd.Parameters.AddWithValue("@CatID", subCatID);
        cmd.Connection = conn;
        try
        {
            conn.Open();
            DataList2.DataSource = cmd.ExecuteReader();
            DataList2.DataKeyField = "SubCatID";
            DataList2.DataBind();
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
        finally
        {
            conn.Close();
            cmd.Dispose();
        }
    }

----------------------------------------- FURTHER UPDATE ---------------------------------------
------------------------------------------------------------------------------------------------
I have added below code to get ID of child datalist control, but it is getting errror: Object reference not set to an instance of an object.

DataList childDataList = (DataList)DataList1.FindControl("DataList2");

On some another site I found below code, but My code not able to recognize item element.

DataList dlSubChild = (DataList)e.Item.FindControl("dlSubChild")