I have created a TextBox dynamically, and i am getting the value of the textbox when i click the button. But the value entered in the dynamic textbox gets empty when i click the button.
Below is my ASPX Code:
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Reports.WebForm1" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<asp:DropDownList ID="DropDownList1" runat="server"
onselectedindexchanged="DropDownList1_SelectedIndexChanged" AutoPostBack = "true">
<asp:ListItem>Text</asp:ListItem>
<asp:ListItem>Check</asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="GetTextBoxValue" />
</form>
</body>
</html>
CodeBehind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Reports
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
TextBox TB = new TextBox();
TB.ID = "abc";
form1.Controls.Add(TB);
Response.Write(Request.Form["abc"]);
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
createcontrol();
}
protected void createcontrol()
{
if (DropDownList1.SelectedValue.ToLower().Trim() == "text")
{
TextBox TB = new TextBox();
TB.ID = "abc";
form1.Controls.Add(TB);
}
}
}
}
When you use dynamic controls in .NET and want their values to be accessible after postback you need to create them within the Page_Init method of the page. In essence its not working because ViewState has already been set by the time you created the controls. See this guide for detailed info on this topic https://web.archive.org/web/20211020131055/https://www.4guysfromrolla.com/articles/081402-1.aspx . To fix the problem elevate your Textbox instantiation code to the Page_Init method and all should be well.
Related
I have an ASP.net WebForm. The markup is like:
<div>
<input type="text" id="input" runat="server" value=" " />
<asp:Button Text="send" OnClick="btnsend_Click" ID="btnsend" runat="server" />
</div>
This HTML is generated at runtime . The events are defined in the code behind file.
I need to add these controls at runtime. I tried to use the Literal-Control but the controls are working just like HTML Controls and not like ASP.net Controls.
EDIT:
Note: The Project type should be Website, not a web Application. Web application won't support on demand compilation where website yes, it is.
If I understood currectly, you want to take the Markup from User which contains even asp.net controls and scriplets too.
if this is the case, Follow below steps:
Create a dummy .ascx control file, like DynamicMarkup.ascx with empty content
Add this user control to the page (xxxx.aspx) where you want to show this control statically so it registered to the page
<%# Register src="~/DynamicMarkup.ascx"
tagname="DynamicMarkup" tagprefix="MyASP" %>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:PlaceHolder runat="server"
ID="DynamicMarkupContainer" ></asp:PlaceHolder>
</div>
</form>
</body>
</html>
Write user input markup (may be get from database based on your criteria) to the DynamicMarkup.ascx file in page OnInit of the page (xxxx.aspx) And the create object of this DynamicMarkup
DynamicMarkup dynamicMarkup = LoadControl("~/DynamicMarkup.ascx") as
DynamicMarkup;
DynamicMarkupContainer.Controls.Add(ucSimpleControl);
I have not tested this approach, Just give a thought, With this you may get some session overwriting issue which you need handle.
Hope this will help!!
OLD:
is this the one that you are expecting? TextBox, and Button controls are available in System.Web.UI.WebControls namespace.
void Page_Load(Object sender, EventArgs e)
{
TextBox input = new TextBox();
input.Id ="input";
this.PlaceHolder.Controls.Add(input);
Button btnSend=new Button();
btnSend.Id ="btnSend";
btnSend.Text="Send";
btnSend.Click += new EventHandler(btnSend_Click);
this.PlaceHolder.Controls.Add(btnSend);
}
void btnSend_Click(object sender, EventArgs e)
{
// throw new NotImplementedException();
}
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!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>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<asp:PlaceHolder ID="phHolder" runat="server"></asp:PlaceHolder>
</form>
</body>
</html>
code behind :
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 Default2 : System.Web.UI.Page
{
protected void Page_Init()
{
GenerateContorls();
}
protected void Page_Load(object sender, EventArgs e)
{
}
private void GenerateContorls()
{
TextBox newTxt = new TextBox() { ID = "txtsend" };
Button newBtn = new Button() { Text = "Send", ID = "btnsend" };
newBtn.Click += btnsend_Click;
phHolder.Controls.Add(newTxt);
phHolder.Controls.Add(newBtn);
}
protected void btnsend_Click(object sender, EventArgs e)
{
TextBox txt = (TextBox)this.FindControl("txtsend");
//your code
}
}
hope it helps
In the sample code there are two listboxes. In ListBox1 the items are defined in Default.aspx. In ListBox2 they are defined in the codefile. ListBox1 behaves as expected, the text box is updated whenever an item is selected. When ListBox2 triggers an event the selectedindex is always -1.
Default.aspx:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="ListBox1" runat="server" OnSelectedIndexChanged="lb1_OnSelectedIndexChanged" AutoPostBack="true">
<asp:ListItem>a</asp:ListItem>
<asp:ListItem>b</asp:ListItem>
</asp:ListBox>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:ListBox ID="ListBox2" runat="server" OnSelectedIndexChanged="lb1_OnSelectedIndexChanged" AutoPostBack="true">
</asp:ListBox>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
</div>
</form>
</body>
</html>
Default.aspx.cs:
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
List<string> ab = new List<string>();
ab.Add("a");
ab.Add("b");
ListBox2.DataSource = ab;
ListBox2.DataBind();
ListBox1.SelectedIndexChanged += new EventHandler(lb1_OnSelectedIndexChanged);
ListBox2.SelectedIndexChanged += new EventHandler(lb2_OnSelectedIndexChanged);
}
protected void lb1_OnSelectedIndexChanged(object sender, EventArgs e)
{
if (ListBox1.SelectedIndex != -1)
{
TextBox1.Text = ListBox1.SelectedItem.Text;
}
}
protected void lb2_OnSelectedIndexChanged(object sender, EventArgs e)
{
if (ListBox2.SelectedIndex != -1)
{
TextBox2.Text = ListBox2.SelectedItem.Text;
}
}
}
The list of items has been moved to Default.aspx to get it working, but I'd really like to know what I'm doing wrong with this. -- Thanks!
You can't databind ListBox2 on every page load. Try:
Page_Load()...
{
if(!IsPostBack)
{
//databind listbox2
}
}
Try reading up a bit on the ASP.NET page lifecycle. On the postback, the ListBox2 will have it's correct state due to viewstate.
Your current code resets it. Hence the -1.
I'm absolutliy confused.
I try to Change the default Text for a Textbox.
Here a simple Code to reproduce the Problem.
TextBox Textbox1 and the label become updated on any click to the Button.
Textbox var will never get updated. Only on first PageLoad.
The Problem is, I have to add my Textboxes from Code behind and not in aspx Page.
Any Ideas whats going on and how I can get it working?
%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="tbtester.WebForm1" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div >
<asp:Panel ID="mypanel" runat="server">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" />
</asp:Panel>
</div>
</form>
</body>
</html>
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace tbtester
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
System.Web.UI.WebControls.TextBox var = new System.Web.UI.WebControls.TextBox();
//if (!this.Page.IsPostBack)
Label test = new Label();
mypanel.Controls.Add(test);
mypanel.Controls.Add(var);
var.Text = DateTime.Now.ToLongTimeString();
test.Text = DateTime.Now.ToLongTimeString();
var.ReadOnly = false;
TextBox1.Text = DateTime.Now.ToLongTimeString();
}
}
}
Disable its read only flag before adding it to your panel:
TextBox var = new TextBox();
var.ReadOnly = false;
mypanel.Controls.Add(var);
I am using FileUpload Control to upload images, I can select the image using that browse button, but when i try to preview that selected one, i am not getting the file name, its showing empty..
protected void btnImgUpload_Click(object sender, ImageClickEventArgs e)
{
try
{
string strimage;
string strfilename, strextn;
if (fupImage.HasFile)
{
In the above code,fupImage.FileName property should have to selected Image name, but it remains as empty string "" , so fubImage.HasFile condition is going false. I am not getting why the condition is going false, while the file is selected,? what is the problem here?
Thanks in advance
what i did to test it is
I create an Asp page
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication2.WebForm1" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:FileUpload ID="fupImage" runat="server" />
<asp:Button ID="btnImageUpload" runat="server" onclick="btnImageUpload_Click"
Text="Upload" />
</div>
</form>
</body>
</html>
and the code behind class is
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebApplication2
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnImageUpload_Click(object sender, EventArgs e)
{
try
{
string strimage;
string strfilename, strextn;
if (fupImage.HasFile)
{
//do something
}
}
catch
{
}
}
}
}
and nothing goes wrong with that
I want to say to test it just create a very simple instance and test it in complex environment may be there are some extra rules may prevents normal jobs! and sometimes it looks so unnoraml
Check for the View-state property of that file uploader Control, If View-state is false, then on post back you'll get empty value
I have a number of pages that I need to Dynamically Load User Controls and process events on controls on them. I have included sample code below for a trivial example.
Default.aspx
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="BtnLoadControl" runat="server" Text="Load Control 1"
onclick="BtnLoadControl_Click" /><br />
<asp:Button ID="BntLoadControl2" runat="server" Text="Load Control 2"
onclick="BntLoadControl2_Click" />
<asp:PlaceHolder ID="ControlArea" runat="server" />
</div>
</form>
</body>
</html>
Deafualt.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void BtnLoadControl_Click(object sender, EventArgs e)
{
Control controlToAdd = Page.LoadControl("~/control1.ascx");
this.ControlArea.Controls.Add(controlToAdd);
}
protected void BntLoadControl2_Click(object sender, EventArgs e)
{
Control controlToAdd = Page.LoadControl("~/control2.ascx");
this.ControlArea.Controls.Add(controlToAdd);
}
}
Control1.ascx
<%# Control Language="C#" AutoEventWireup="true" CodeFile="control1.ascx.cs" Inherits="control1" %>
<div style="border: 1px solid red;">Test Control
<br /><asp:Button runat="server" ID="testButton" Text="test" onclick="testButton_Click" /></div>
Control1.ascx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class control1 : System.Web.UI.UserControl
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void testButton_Click(object sender, EventArgs e)
{
Response.Write("Button Clicked on Control 1!");
}
}
Control2.ascx
<%# Control Language="C#" AutoEventWireup="true" CodeFile="Control2.ascx.cs" Inherits="Control2" %>
<div style="border: 1px solid red;">Test Control 2
<br /><asp:Button runat="server" ID="testButton2" Text="test me"
onclick="testButton2_Click" /></div>
Control2.ascx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Control2 : System.Web.UI.UserControl
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void testButton2_Click(object sender, EventArgs e)
{
Response.Write("Button Clicked on Control 2!");
}
}
This is a very trivial example to show what I would like to do. My actual control is more complex and has several properties that I set for the control I load as I load it (in the default.aspx.cs files event handler).
With this example what happens is when the button is clicked on one of the loaded controls, the page is re-loaded and the control is no longer there. How can I keep the control loaded as well as process any events that happen on the control?
You're asking if you can keep the control loaded in the page?
You can't keep the control loaded in the page, because the page doesn't exist! It's recreated on every request. It's created from the markup (compiled or not), and from running any code in the CodeBehind. If you want your controls to be there after a PostBack, then you need to recreate them on the PostBack. If you want to process events on those controls, then you'll have to wire the controls to event handlers when you recreate them after PostBack. Then the events will fire.