How to add own event handler in C#

Question

User-1773939321 posted

  I found this article very useful while adding control in dynamically.

 http://www.codeproject.com/KB/user-controls/DynamicUC.aspx

But when converting VB to C# I am facing problem in the event Handler.

 

//Add an event handler to this control to raise an event when the delete button is clicked

            //on the user control

            //DynamicUserControl.RemoveUserControl += this.HandleRemoveUserControl;

            DynamicUserControl.RemoveUserControl += new EventHandler(RemoveUserControl);

 

 

void RemoveUserControl(object sender, EventArgs e)

    {

        //This handles delete event fired from the user control

 

        //Get the user control that fired this event, and remove it

        Admin_AddPhoto DynamicUserControl = sender.parent;

        ph1.Controls.Remove(sender.parent);

 

        //Keep a pipe delimited list of which user controls were removed. This will increase the

        //viewstate size if the user keeps removing dynamic controls, but under normal use

        //this is such a small increase in size that it shouldn't be an issue.

        ltlRemoved.Text += DynamicUserControl.ID + "|";// ERROR: Unknown assignment operator ConcatString ;

 

        //Also, now that we've removed a user control decrement the count of total user controls on the page

        ltlCount.Text = Convert.ToString((Convert.ToInt16(ltlCount.Text) - 1));

        throw new Exception("The method or operation is not implemented.");

       

    }

 

But when I call the “sender.Parent” here I am getting error

 

Error      1              'object' does not contain a definition for 'parent'           

 

How to remove the error. ? ???????

 

 

Answer 1

User-2058416358 posted
Hi place ((Control)sender).Parent in place of sender.parent and try.

Answer 2

User-1824631895 posted

sender is an object variable and obviously, object do not possess a Parent property. try casting sender to the appropriate type. and calling the parent property on that type

e.g

Control ctrl = (Control)sender;

Admin_AddPhoto DynamicUserControl = bttn.Parent;

 

thats it.

 

Answer 3

User251781917 posted

You need to cast sender to the appropriate class type. For example:

 
1    void EventHandlerMethod(object sender, EventArgs e) 
2    {
3        Button button = sender as Button;
4        Admin_AddPhoto dynamicUserControl = button.Parent;
5    
6        // put remaining functionality here
7    }
 

I hope this helps. 

Answer 4

User-1773939321 posted

 Thanks aggiekevin,

Have you read the link of CodeProject which i sent to to if you try it it's working but it is written VB. How can i convert and use in C#.........................?????????????

Answer 5

User-1228306975 posted

----- default page ----

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Text;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        AddAndRemoveDynamicControls();
    }

    private void AddAndRemoveDynamicControls()
    {
        Control c = new Control();
        c = GetPostBackControl(Page);
        if (c != null)
        {
            if (c.ID.ToString() == "btnAdd")
            {
                ltlCount.Text = (Convert.ToInt16(ltlCount.Text) + 1).ToString();
            }
        }
        ph1.Controls.Clear();
        int ControlID = 0;

        for (int i = 0; i <= (Convert.ToInt16(ltlCount.Text) - 1); i++)
        {
            WebUserControl DynamicUserControl = LoadControl("WebUserControl.ascx") as WebUserControl;
            while (InDeletedList("uc" + ControlID) == true)
            {
                ControlID += 1;
            }
            DynamicUserControl.ID = "uc" + ControlID;
            DynamicUserControl.RemoveUserControl += new EventHandler(HandleRemoveUserControl);
            ph1.Controls.Add(DynamicUserControl);
            ControlID += 1;
        }
    }

    public void HandleRemoveUserControl(object sender, EventArgs e)
    {
        Button but = sender as Button;
        WebUserControl DynamicUserControl = (WebUserControl)but.Parent;
        ph1.Controls.Remove(DynamicUserControl);
        ltlRemoved.Text += DynamicUserControl.ID + "|";
        ltlCount.Text = (Convert.ToInt16(ltlCount.Text) - 1).ToString();
    }

    private bool InDeletedList(string ControlID)
    {
        string[] DeletedList = ltlRemoved.Text.Split(new string[] { "|" }, StringSplitOptions.None);
        for (int i = 0; i < DeletedList.GetLength(0) - 1; i++)
        {
            if (ControlID.ToLower() == DeletedList[i].ToLower())
            {
                return true;
            }
        }
        return false;
    }

    public Control GetPostBackControl(Page Page)
    {
        Control control = null;

        string ctrlname = Page.Request.Params.Get("__EVENTTARGET");
        if (ctrlname != null && ctrlname != string.Empty)
        {
            control = Page.FindControl(ctrlname);
        }
        else
        {
            foreach (string ctl in Page.Request.Form)
            {
                Control c = Page.FindControl(ctl);
                if (c is System.Web.UI.WebControls.Button)
                {
                    control = c;
                    break;
                }
            }
        }
        return control;
    }

    protected void btnDisplayValues_Click(object sender, EventArgs e)
    {
        ltlValues.Text = "";
        foreach (Control c in ph1.Controls)
        {

            if (c.GetType().Name.ToString() == "webusercontrol_ascx")
            {
                UserControl uc = (UserControl)c;
                TextBox tbx1 = (TextBox)uc.FindControl("tbx1");
                DropDownList ddl1 = (DropDownList)uc.FindControl("ddl1");
                CheckBoxList cbx1 = (CheckBoxList)uc.FindControl("cbx1");

                StringBuilder sb = new StringBuilder();
                sb.Append("Textbox value: " + tbx1.Text + "<br />");
                sb.Append("Dropdown value: " + ddl1.SelectedValue + "<br />");
                sb.AppendLine("Checkbox values: ");

                foreach (ListItem li in cbx1.Items)
                {
                    if (li.Selected == true)
                    {
                        sb.Append(li.Value + "<br />");
                    }
                }

                sb.Append("<hr />");

                ltlValues.Text += sb.ToString();
            }
        }
    }
}

 

------ WebUserControl.ascx.cs -------

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class WebUserControl : System.Web.UI.UserControl
{
    public event EventHandler RemoveUserControl;

    protected void btnRemove_Click(object sender, EventArgs e)
    {
        if (RemoveUserControl != null)
        {
            RemoveUserControl(sender, e);
        }
    }
}
 

 

------- WebUserControl.ascx ------

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>

    <table>
        <tr>
            <td>Textbox Example:</td>
            <td>
                <asp:TextBox ID="tbx1" runat="server" />
            </td>
        </tr>
        <tr>
            <td>Dropdown Example:</td>
            <td>
                <asp:DropDownList ID="ddl1" runat="server">
                    <asp:ListItem Text="Dropdown 1" />
                    <asp:ListItem Text="Dropdown 2" />
                    <asp:ListItem Text="Dropdown 3" />
                </asp:DropDownList>
            </td>
        </tr>
        <tr>
            <td>Checkbox Example:</td>
            <td>
                <asp:CheckBoxList ID="cbx1" runat="server">
                    <asp:ListItem Text="Checkbox 1" />
                    <asp:ListItem Text="Checkbox 2" />
                    <asp:ListItem Text="Checkbox 3" />
                </asp:CheckBoxList>
            </td>
        </tr>
    </table>
    <asp:Button ID="btnRemove" runat="server" Text="Remove" OnClick="btnRemove_Click" />

 ------ Default.aspx -------

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<%@ Register src="WebUserControl.ascx" tagname="WebUserControl" tagprefix="uc1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Dynamic User Control Demo</title>
    <style type="text/css">
        div.demo

        {
           width:300px;
           float:left;
           padding:20px;
           margin: 10px;
           border: solid black 1px;        
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
       
        <asp:UpdatePanel ID="up1" runat="server">
            <ContentTemplate>
                <div class="demo">
                    <asp:PlaceHolder ID="ph1" runat="server"></asp:PlaceHolder>
                    <asp:Button ID="btnAdd" runat="server" Text="Add" />
                </div>
                <div class="demo">
                    <asp:Literal ID="ltlValues" runat="server"></asp:Literal>
                    <asp:Button ID="btnDisplayValues" runat="server" Text="Display Values"
                        onclick="btnDisplayValues_Click" />
                </div>
            </ContentTemplate>
        </asp:UpdatePanel>
       
        <asp:Literal ID="ltlCount" runat="server" Text="0" Visible="false"></asp:Literal>
        <asp:Literal ID="ltlRemoved" runat="server" Visible="false"></asp:Literal>
    </div>
    </form>
</body>
</html>
 

 

Answer 6

User251781917 posted

 Thanks aggiekevin,

Have you read the link of CodeProject which i sent to to if you try it it's working but it is written VB. How can i convert and use in C#.........................?????????????

 

 

Hi Hamza,

If you still need to convert code from VB to C# (or vice versa), I highly recommend trying Telerik's Code Converter, which allows you to easily convert code between the two languages. Check it out at this link.

I hope that helps.

Answer 7

User-1940854371 posted

Hi here i post easiest way to add and remove web user control dynamically

webuser control ascx page :

AddTier.ascx

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="AddTier.ascx.cs" Inherits="AddTier" %>
<tr>
    <td>
        <asp:Label runat="server" ID="lblTier"></asp:Label>
    </td>
    <td>
        <asp:DropDownList runat="server" ID="drp">
            <asp:ListItem Selected="True">$</asp:ListItem>
            <asp:ListItem Value="%"></asp:ListItem>
        </asp:DropDownList>
    </td>
    <td>
        <asp:TextBox runat="server" ID="txt"></asp:TextBox>
        <asp:RequiredFieldValidator runat="server" ID="reqtxt" ControlToValidate="txt" ErrorMessage="*"></asp:RequiredFieldValidator>
    </td>
</tr>

page for dynamically add this control :

TestConrol.aspx

            <asp:Button runat="server" ID="btnSaleTier" Text="Add Tier" OnClick="btnSaleTier_Click" />
            <asp:Button runat="server" ID="btnSaleRemove" Text="Remove Last Tier" OnClick="btnSaleRemove_Click" />
            <table>
                <asp:Panel runat="server" ID="pnlAddSaleTier">
                </asp:Panel>
            </table>

TestControl.aspx.cs

protected void Page_Load(object sender, EventArgs e)
    {

  int num = 0;
        if (ViewState["Counter"] != null)
        {
            num = (int)ViewState["Counter"];
        }
        else
        {
            ViewState["Counter"] = 0;
        }
        for (int j = 0; j < num; j++)
        {
            Control cl = LoadControl("~/AddTier.ascx");

            cl.ID = "c" + j;
            if (pnlAddSaleTier.FindControl(cl.ID) != null)
            {

            }
            else
            {
                pnlAddSaleTier.Controls.Add(cl);
            }
        }
        if (ViewState["Remove"] == "1")
        {
            pnlAddSaleTier.Controls.RemoveAt(Convert.ToInt32(ViewState["Counter"]));
        }

}

    protected void btnSaleTier_Click(object sender, EventArgs e)
    {
        ViewState["Counter"] = (int)ViewState["Counter"] + 1;
        Page_Load(Page, new EventArgs());
    }

 protected void btnSaleRemove_Click(object sender, EventArgs e)
    {
     
        ViewState["Remove"] = "1";
        Page_Load(Page, new EventArgs());
        ViewState["Remove"] = "0";
        ViewState["Counter"] = (int)ViewState["Counter"] - 1;
    }

Hope this will help you.

http://khushi20.blogspot.com/

http://jayeshmodasa.wordpress.com/

Best Regards,

Jayesh Patel

Answer 8

User1239874837 posted

Thanks very much!

This is what I want.

Answer 9

User346727691 posted

i try this last easy example but give me debug said , 

 



The name 'pnlAddSaleTier' does not exist in the current context

Answer 10

User346727691 posted

wangbang , could you please help me , wich one you have been using of this 2 examples , because the first one is too long i think and the second make the same work but with less code and effort , right ?

send me back please

Answer 11

User1590754065 posted

HI All! both the above codes work fine. But how about having a file upload control in the User control..??