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Dynamically adding custom control

RE: Dynamically adding custom control

stcheng NO[at]SPAM online.microsoft.com
11/17/2005 12:00:00 AM

asp.net building controls:

Dynamically adding custom control

Terry Holland
11/17/2005 9:28:24 PM

Im trying to dynamically add a user control for a webform but it is not
appearing when I run the form.

I have pasted the code that I am using. Can someone advise what Im doing
wrong. My user control (ctlTextBox) contains one textbox. When I dragged
this onto the control, the line

Protected WithEvents txt As System.Web.UI.WebControls.TextBox

was added the declarations area of the code module. Without changing this
to

Protected WithEvents txt As New System.Web.UI.WebControls.TextBox

An error is generated on my page as soon as I hit the line

.Text = "Tesing Control"

Also, if I drag ctlTextBox onto my form at design time, it displays OK

==========================
User Control Code
==========================
Public Class ctlTextBox
Inherits System.Web.UI.UserControl

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub

'############################################################
'## This is the code that was generated
############
'## but without the New keyword, a runtime error is generated
############
'## when I try to set the Text property on the page
############
'############################################################
'Protected WithEvents txt As System.Web.UI.WebControls.TextBox
Protected WithEvents txt As New System.Web.UI.WebControls.TextBox

'NOTE: The following placeholder declaration is required by the Web Form
Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

Public Property Width() As Integer
Get
Return txt.Width.Value
End Get
Set(ByVal Value As Integer)
txt.Width = Unit.Pixel(Value)
End Set
End Property

Public Property Text() As String
Get
Return txt.Text
End Get
Set(ByVal Value As String)
txt.Text = Value
End Set
End Property

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
txt.CssClass = "Editable"
End Sub

End Class
===========================
End User Control Code
===========================

===========================
Page Code
===========================
Public Class pgeTest
Inherits System.Web.UI.Page

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub

Protected WithEvents Panel1 As System.Web.UI.WebControls.Panel

'NOTE: The following placeholder declaration is required by the Web Form
Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
BuildControls()
End Sub

Sub BuildControls()
Dim tb As New ctlTextBox
With tb
.Text = "Tesing Control"
End With
Panel1.Controls.Add(tb)

Dim txt As New TextBox
txt.Text = "Hello"
Panel1.Controls.Add(txt)

Dim lbl As New Label
lbl.Text = "Label"
Panel1.Controls.Add(lbl)

End Sub

End Class
===============================
End of Page Code
===============================

Re: Dynamically adding custom control

Terry Holland
11/18/2005 12:00:00 AM

We meet again Steven.

Ive modified my code to remove the New keyword and added the LoadControl
method in my page to load the control and now the user control appears on
the screen.

Thanks

Terry Holland

[quoted text, click to view]

Re: Dynamically adding custom control

stcheng NO[at]SPAM online.microsoft.com
11/19/2005 12:00:00 AM

You're welcome Terry,

Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
--------------------
| From: "Terry Holland" <terryeholland@newsgroup.nospam>
| References: <#l8Ze376FHA.1188@TK2MSFTNGP12.phx.gbl>
<jlvfhG$6FHA.832@TK2MSFTNGXA02.phx.gbl>
| Subject: Re: Dynamically adding custom control
| Date: Fri, 18 Nov 2005 15:12:33 -0000
| Lines: 218
| X-Priority: 3
| X-MSMail-Priority: Normal
| X-Newsreader: Microsoft Outlook Express 6.00.2900.2527
| X-RFC2646: Format=Flowed; Original
| X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527
| Message-ID: <OCSgHKF7FHA.1416@TK2MSFTNGP09.phx.gbl>
| Newsgroups: microsoft.public.dotnet.framework.aspnet.buildingcontrols
| NNTP-Posting-Host: host225.multiserv.com 194.200.135.225
| Path: TK2MSFTNGXA02.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP09.phx.gbl
| Xref: TK2MSFTNGXA02.phx.gbl
microsoft.public.dotnet.framework.aspnet.buildingcontrols:14006
| X-Tomcat-NG: microsoft.public.dotnet.framework.aspnet.buildingcontrols
|
| We meet again Steven.
|
| Ive modified my code to remove the New keyword and added the LoadControl
| method in my page to load the control and now the user control appears on
| the screen.
|
| Thanks
|
| Terry Holland
|
|
[quoted text, click to view]
| > Hi Terry,
| >
| > As for ASP.NET Usercontrol(ascx...), the Control instances are all
defined
| > in the .ascx template file(if not dynamically adding control...), so we
| > should not declare "New" for control reference like:
| >
| > Protected WithEvents txt As New System.Web.UI.WebControls.TextBox
| >
| > If you get error when not using "New", there must have something
incorrect
| > in our page or code logic. Would you also provide the ascx template
| > together with the code behind?
| >
| > In addition, for dynamically adding Usercontrol onto aspx page, we
should
| > use the Page.LoadControl method to load the "xxx.ascx" so as to create
the
| > UserControl instance and add it into Container control in each Page
| > Request....
| >
| > If there're anything unclear, please feel free to post here.
| >
| > Regards,
| >
| > Steven Cheng
| > Microsoft Online Support
| >
| > Get Secure! www.microsoft.com/security
| > (This posting is provided "AS IS", with no warranties, and confers no
| > rights.)
| >
| >
| > --------------------
| > | From: "Terry Holland" <terryeholland@newsgroup.nospam>
| > | Subject: Dynamically adding custom control
| > | Date: Thu, 17 Nov 2005 21:28:24 -0000
| > | Lines: 149
| > | X-Priority: 3
| > | X-MSMail-Priority: Normal
| > | X-Newsreader: Microsoft Outlook Express 6.00.2900.2527
| > | X-RFC2646: Format=Flowed; Original
| > | X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527
| > | Message-ID: <#l8Ze376FHA.1188@TK2MSFTNGP12.phx.gbl>
| > | Newsgroups: microsoft.public.dotnet.framework.aspnet.buildingcontrols
| > | NNTP-Posting-Host: host10.harsco.com 209.183.189.10
| > | Path: TK2MSFTNGXA02.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP12.phx.gbl
| > | Xref: TK2MSFTNGXA02.phx.gbl
| > microsoft.public.dotnet.framework.aspnet.buildingcontrols:13997
| > | X-Tomcat-NG: microsoft.public.dotnet.framework.aspnet.buildingcontrols
| > |
| > | Im trying to dynamically add a user control for a webform but it is
not
| > | appearing when I run the form.
| > |
| > | I have pasted the code that I am using. Can someone advise what Im
| > doing
| > | wrong. My user control (ctlTextBox) contains one textbox. When I
| > dragged
| > | this onto the control, the line
| > |
| > | Protected WithEvents txt As System.Web.UI.WebControls.TextBox
| > |
| > | was added the declarations area of the code module. Without changing
| > this
| > | to
| > |
| > | Protected WithEvents txt As New System.Web.UI.WebControls.TextBox
| > |
| > | An error is generated on my page as soon as I hit the line
| > |
| > | .Text = "Tesing Control"
| > |
| > | Also, if I drag ctlTextBox onto my form at design time, it displays OK
| > |
| > |
| > | ==========================
| > | User Control Code
| > | ==========================
| > | Public Class ctlTextBox
| > | Inherits System.Web.UI.UserControl
| > |
| > | #Region " Web Form Designer Generated Code "
| > |
| > | 'This call is required by the Web Form Designer.
| > | <System.Diagnostics.DebuggerStepThrough()> Private Sub
| > | InitializeComponent()
| > |
| > | End Sub
| > |
| > | '############################################################
| > | '## This is the code that was generated
| > | ############
| > | '## but without the New keyword, a runtime error is generated
| > | ############
| > | '## when I try to set the Text property on the page
| > | ############
| > | '############################################################
| > | 'Protected WithEvents txt As System.Web.UI.WebControls.TextBox
| > | Protected WithEvents txt As New System.Web.UI.WebControls.TextBox
| > |
| > | 'NOTE: The following placeholder declaration is required by the
Web
| > Form
| > | Designer.
| > | 'Do not delete or move it.
| > | Private designerPlaceholderDeclaration As System.Object
| > |
| > | Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
| > | System.EventArgs) Handles MyBase.Init
| > | 'CODEGEN: This method call is required by the Web Form
Designer
| > | 'Do not modify it using the code editor.
| > | InitializeComponent()
| > | End Sub
| > |
| > | #End Region
| > |
| > | Public Property Width() As Integer
| > | Get
| > | Return txt.Width.Value
| > | End Get
| > | Set(ByVal Value As Integer)
| > | txt.Width = Unit.Pixel(Value)
| > | End Set
| > | End Property
| > |
| > | Public Property Text() As String
| > | Get
| > | Return txt.Text
| > | End Get
| > | Set(ByVal Value As String)
| > | txt.Text = Value
| > | End Set
| > | End Property
| > |
| > | Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
| > | System.EventArgs) Handles MyBase.Load
| > | 'Put user code to initialize the page here
| > | txt.CssClass = "Editable"
| > | End Sub
| > |
| > | End Class
| > | ===========================
| > | End User Control Code
| > | ===========================
| > |
| > |
| > | ===========================
| > | Page Code
| > | ===========================
| > | Public Class pgeTest
| > | Inherits System.Web.UI.Page
| > |
| > | #Region " Web Form Designer Generated Code "
| > |
| > | 'This call is required by the Web Form Designer.

Re: Dynamically adding custom control

Terry Holland
11/22/2005 12:00:00 AM

Steven

Im getting in a bit of a mess with this. What I want to end up with is a
set of controls for editing / displaying fields on a webform. I would like
to be able to dynamically add these controls to webforms as and when I need
them.

Initially I need three types of fields

ctlFieldReadOnly
ctlFieldEditable
ctlFieldEditableRequired

Each of these controls will consist of the following controls:

ctlFieldReadOnly: Label (lblLabel) and a label (lblValue) to display the
data
ctlFieldEditable: Label (lblLabel) and a textbox (txtValue - background
colour blue) to the display the data
ctlFieldEditableRequired: Label (lblLabel) and a textbox (txtValue -
background colour yellow) to the display the data.

Each of these controls needs to expose a Label property and a Value
property.
Each control should be able to be configured so the either, the Label
control is above the Value control, or the Label control appears to the Left
of the Value control.

Each form may contain any number of each type of control.

Ive been trying to develop along the following lines:
Create a Base control such as ctlField that must be inherited. This control
will contain the properties Label, Value, Width and HorizontalAlignment.
Im then trying to derive the required controls from this control. My derived
controls should add the relevant webcontrols ie Label to display the Value
for a ctlReadOnly control, a Textbox to display the Value for
ctlFieldEditable & ctlFieldEditableRequired controls.
Im getting various results ranging from no controls being displayed, not
being able to refer to controls in order to read/write values.

It would be very helpful if you could provide a small sample of how I might
get this sort of scenario to work (VB if possible - I know you prefer C#)

Terry

[quoted text, click to view]

Unable to access my user control.

DS
11/22/2005 6:50:23 AM

Hi steven,

I have a similar problem as Terry. I have a user control. I add this user
control to a ASP:TABLE in my aspx page in the code behind using LoadControl
method n number of times. When the page is rendered, i could see the all the
n copies of my user control. I have a submit button in my page, when I click
this button I post back to the same page but do a different functionality.
Now the problem is I am not able to access any of the usercontrols. How do I
refer to my usercontrol and the textboxes inside my user control.

Need ur help.
D. Santhosh

[quoted text, click to view]

Re: Dynamically adding custom control

stcheng NO[at]SPAM online.microsoft.com
11/23/2005 12:00:00 AM

Re: Dynamically adding custom control

Terry Holland
11/25/2005 6:57:20 PM

Ok. This is what I am trying.

I have a base control called ctlField. From this I derive another few
controls, one of which is ctlFieldHEditableRequired.

I am placing a ctlFieldHEditableRequired and a Button onto my page
WebForm1.aspx.

When I click my button I want to use the values from my
ctlFieldHEditableRequired control to save to a database. However, when I
click my button, the values that I retrieve from my user control do not
reflect any changes that were made.
I have pasted enough of a a sample of my code to demonstrate the problems
that Im having. If I run my project the values in my control are
Label: New Label
Textbox: New Value

If I change the value in the Textbox to XXX and click the button on the
page, the value that gets written to the page is New Value instead of XXX.
How do I overcome this problem?

BASE CONTROL HTML -ctlField
=========================
<%@ Control Language="vb" AutoEventWireup="false"
Codebehind="ctlField.ascx.vb" Inherits="UserControl.ctlField"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5" %>

BASE CONTROL CODE BEHIND
=========================
Public Class ctlField
Inherits System.Web.UI.UserControl

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub

'NOTE: The following placeholder declaration is required by the Web Form
Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region
Protected m_intLabelWidth As Integer = 100
Protected m_intValueWidth As Integer = 150
Protected m_strLabel As String = "Label"
Protected m_strValue As String = "Value"

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
End Sub

Public Property LabelWidth() As Integer
Get
Return m_intLabelWidth
End Get
Set(ByVal Value As Integer)
m_intLabelWidth = Value
End Set
End Property

Public Property ValueWidth() As Integer
Get
Return m_intValueWidth
End Get
Set(ByVal Value As Integer)
m_intValueWidth = Value
End Set
End Property

Public Property Label() As String
Get
Return m_strLabel
End Get
Set(ByVal Value As String)
m_strLabel = Value
End Set
End Property

Public Property Value() As String
Get
Return m_strValue
End Get
Set(ByVal Value As String)
m_strValue = Value
End Set
End Property
End Class

DERIVED CONTROL HTML - ctlFieldHEditableRequired
=========================================
<%@ Control Language="vb" AutoEventWireup="false"
Codebehind="ctlFieldHEditableRequired.ascx.vb"
Inherits="UserControl.ctlFieldHEditableRequired"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5" %>
<asp:label id="Label1" Width="496px"
runat="server">Label</asp:label><asp:textbox id="TextBox1" Width="16px"
runat="server"></asp:textbox>

DERIVED CONTROL CODE BEHIND
=============================
Public Class ctlFieldHEditableRequired
Inherits ctlField ' System.Web.UI.UserControl

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub

Protected WithEvents Label1 As System.Web.UI.WebControls.Label
Protected WithEvents TextBox1 As System.Web.UI.WebControls.TextBox

'NOTE: The following placeholder declaration is required by the Web Form
Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
If IsPostBack Then Exit Sub

With Label1
.Width = Unit.Pixel(m_intLabelWidth)
.Text = m_strLabel
End With

With TextBox1
.Width = Unit.Pixel(m_intValueWidth)
.Text = m_strValue
.CssClass = "FieldEditableRequired"
End With

End Sub

End Class

WebForm1 HTML
==============
<%@ Register TagPrefix="uc1" TagName="ctlFieldHEditableRequired"
Src="ctlFieldHEditableRequired.ascx" %>
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="WebForm1.aspx.vb"
Inherits="UserControl.WebForm1"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>WebForm1</title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<P>
<uc1:ctlFieldHEditableRequired id="ctlFieldHEditableRequired1"
runat="server"></uc1:ctlFieldHEditableRequired></P>
<P>
<asp:Button id="Button1" runat="server" Text="Button"></asp:Button></P>
</form>
</body>
</HTML>

WebForm1 CODEBEHIND
===================
Public Class WebForm1
Inherits System.Web.UI.Page

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

End Sub

Protected WithEvents ctlFieldHEditableRequired1 As
ctlFieldHEditableRequired
Protected WithEvents Button1 As System.Web.UI.WebControls.Button

'NOTE: The following placeholder declaration is required by the Web Form
Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

Re: Dynamically adding custom control

Terry Holland
11/26/2005 9:47:06 PM

Steven

I just realised Im using wrong terminology. Im not creating "Custom
Controls", I'm creating "User Controls".

Apologies for any confusion

Terry

Re: Dynamically adding custom control

stcheng NO[at]SPAM online.microsoft.com
11/28/2005 7:55:10 AM

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