user controls: dynamiclly added child controls dont survive post back ?

W

Wolfgang Brucker

hi,

i have some strange behaviour: i've created a web user control that add's
some child controls (e.g: textbox, image buttons) to its control collection
(= Me.Controls) at runtime.

no prob. but after a postback gets fired (and the web page reloads) the
control collectionb (Me.Controls) is NOTHING. where are the controls
that i've added?

i even tryed to replace Me.Controls with my own collection, but the very
same effect occurs (value of NOTHING after postback).

what the hell i'm doing wrong (code incl.) and what do i have to do
to make the added child controls surviving a post back ?

thx,
wolfgang brucker
delphi software



############ Code comes here ############

Imports System

Imports System.ComponentModel

Imports System.Text

Imports System.Web

Imports System.Web.UI

Imports System.Web.UI.WebControls



Namespace WebControls



Public Enum en_TV_Resolution

PAL_160x120

PAL_320x240

PAL_352x288

PAL_352x576

PAL_480x576

PAL_720x576

PAL_768x608

End Enum



Public Enum en_ctrlITVcontent_ChildControlType

TextBox

DynamicTextBox

ImageButton

End Enum



<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissi
ons.SecurityAction.Demand, Name:="FullTrust")> _

Public Class ctrlITVcontent

Inherits WebControl

Implements IPostBackEventHandler

Implements INamingContainer

Public Event Click As EventHandler



Private myTVResolution As en_TV_Resolution

Private myCOL As New Collection







<Description("Gets or sets the original TV Resolution in Pixel."), _

Category("Layout"), _

DefaultValue(en_TV_Resolution.PAL_720x576)> _

Public Property OriginalTVResolution() As en_TV_Resolution

Get

Return myTVResolution

End Get

Set(ByVal Value As en_TV_Resolution)

myTVResolution = Value

End Set

End Property







Public Sub AddNewTextBox(ByVal PosX As Integer, ByVal PosY As Integer, ByVal
TVWidth As Integer, _

Optional ByVal InitText As String = "")

If TVWidth = 0 Then

Exit Sub

End If

Dim ctrl As New System.Web.UI.WebControls.TextBox

Dim css As String = "POSITION: absolute; "

Dim x As Integer = TVpx2PCpx_Width(PosX)

Dim y As Integer = TVpx2PCpx_Height(PosY)

Dim w As Integer = TVSize2PCSize_Width(TVWidth) 'TVpx2PCpx_Width(TVWidth)

css &= "LEFT: " & x.ToString & "px; "

css &= "TOP: " & y.ToString & "px;"

ctrl.Attributes.Add("style", css)

ctrl.Attributes.Add("width", w)

ctrl.Width = Unit.Pixel(w)

ctrl.Text = InitText

ctrl.ID = CreateID(en_ctrlITVcontent_ChildControlType.TextBox)

Me.Controls.Add(ctrl)

myCOL.Add(ctrl)

End Sub



Public Sub AddNewDynamicTextBox(ByVal PosX As Integer, ByVal PosY As
Integer, ByVal TVSize_W As Integer, _

' ...

' like "AddNewTextBox"

' ....

End Sub





Public Sub AddNewImageButton(ByVal PosX As Integer, ByVal PosY As Integer,
ByVal TVSize As Byte, _

ByVal PictureURL As String)

' ...

' like "AddNewTextBox"

' ...

End Sub



Public Sub RemoveAllChildControls()

If HasControls() Then

Dim i As Integer

For i = Controls.Count - 1 To 0 Step -1

Controls(i).Dispose()

Next

End If

End Sub



Private Function PAL_Width() As Integer

Select Case OriginalTVResolution

Case en_TV_Resolution.PAL_160x120 : Return 160

Case en_TV_Resolution.PAL_320x240 : Return 320

Case en_TV_Resolution.PAL_352x288 : Return 352

Case en_TV_Resolution.PAL_352x576 : Return 352

Case en_TV_Resolution.PAL_480x576 : Return 480

Case en_TV_Resolution.PAL_720x576 : Return 720

Case en_TV_Resolution.PAL_768x608 : Return 768

End Select

End Function



Private Function PAL_Height() As Integer

Select Case OriginalTVResolution

Case en_TV_Resolution.PAL_160x120 : Return 160

Case en_TV_Resolution.PAL_320x240 : Return 240

Case en_TV_Resolution.PAL_352x288 : Return 288

Case en_TV_Resolution.PAL_352x576 : Return 576

Case en_TV_Resolution.PAL_480x576 : Return 576

Case en_TV_Resolution.PAL_720x576 : Return 576

Case en_TV_Resolution.PAL_768x608 : Return 608

End Select

End Function



' size 1=1/1 2=1/2 4=1/4 8=1/8 des fernse-bildes (und sogleich in PC-Pixel
ummappen)

Private Function TVSize2PCSize_Width(ByVal TVSize As Integer) As Integer

Return TVpx2PCpx_Width(PAL_Width() * (1 / TVSize))

End Function

Private Function TVSize2PCSize_Height(ByVal TVSize As Integer) As Integer

Return TVpx2PCpx_Height(PAL_Height() * (1 / TVSize))

End Function

' PosX [tv] = 240 => wird in diesem Ctrl auf PosX [pc] = 166 gemappt

Private Function TVpx2PCpx_Width(ByVal TVPosX As Integer) As Integer

Return CInt(TVPosX / (PAL_Width() / Val(Me.Width.ToString)))

End Function

Private Function TVpx2PCpx_Height(ByVal TVPosY As Integer) As Integer

Return CInt(TVPosY / (PAL_Height() / Val(Me.Height.ToString)))

End Function



Private Function CreateID(ByVal ctrl_type As
en_ctrlITVcontent_ChildControlType) As String

Dim id_nr As Integer = Me.Controls.Count

Dim kz As String

Select Case ctrl_type

Case en_ctrlITVcontent_ChildControlType.TextBox : kz = "txtPreV" &
CStr(id_nr)

Case en_ctrlITVcontent_ChildControlType.DynamicTextBox : kz =
"txtCtrlPreView" & (id_nr)

Case en_ctrlITVcontent_ChildControlType.ImageButton : kz = "imgCtrlPreView"
& (id_nr)

End Select

Return kz

End Function



'Protected Overrides Sub AddAttributesToRender(ByVal writer As
System.Web.UI.HtmlTextWriter)

''


'End Sub



' invoke delegates registered with the click event.

Protected Overridable Sub OnClick(ByVal e As EventArgs)

RaiseEvent Click(Me, e)

End Sub

' raise click event to owner of this control

Public Sub RaisePostBackEvent(ByVal eventArgument As String) Implements
System.Web.UI.IPostBackEventHandler.RaisePostBackEvent

OnClick(New EventArgs)

End Sub



Protected Overrides Sub CreateChildControls()

Me.InitializeComponent()

End Sub



Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

MyBase.OnPreRender(e)

End Sub

Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)

Me.EnsureChildControls()

MyBase.Render(writer)

End Sub

Private Sub InitializeComponent()

If Me.Controls Is Nothing Then

Dim ctrl As Control

For Each ctrl In myCOL

Me.Controls.Add(ctrl)

Next

End If

End Sub





Private Sub EventHandler_ImageClicked(ByVal sender As Object, ByVal e As
System.Web.UI.ImageClickEventArgs)

Dim x As String

x = ""

End Sub



Private Sub EventHandler_DynamicTextChanged(ByVal sender As Object, ByVal e
As System.EventArgs)

Dim x As String

x = ""

End Sub



Protected Overrides Sub RenderChildren(ByVal writer As
System.Web.UI.HtmlTextWriter)

If HasControls() Then

Dim i As Integer

Dim c As New Control

For i = Controls.Count - 1 To 0 Step -1

Controls(i).RenderControl(writer)

Next

End If

End Sub

Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)

'

End Sub

End Class

End Namespace





############ CODE-END ############
 
V

Victor Garcia Aprea [MVP]

Hi Wolfgang,

Are you always recreating the child controls (no matter IsPostBack value,
etc) ? You need to recreate them every time for them to be available as
there is no builtin support to "remember" which controls were previously
created.
Also, when you start dealing with dynamically created controls it may be
better to start looking for a composite custom control instead of a Web User
Control.

--
Victor Garcia Aprea
Microsoft MVP | ASP.NET
Looking for insights on ASP.NET? Read my blog:
http://obies.com/vga/blog.aspx

To contact me remove 'NOSPAM'. Please post all questions to the newsgroup
Wolfgang Brucker said:
hi,

i have some strange behaviour: i've created a web user control that add's
some child controls (e.g: textbox, image buttons) to its control collection
(= Me.Controls) at runtime.

no prob. but after a postback gets fired (and the web page reloads) the
control collectionb (Me.Controls) is NOTHING. where are the controls
that i've added?

i even tryed to replace Me.Controls with my own collection, but the very
same effect occurs (value of NOTHING after postback).

what the hell i'm doing wrong (code incl.) and what do i have to do
to make the added child controls surviving a post back ?

thx,
wolfgang brucker
delphi software



############ Code comes here ############

Imports System

Imports System.ComponentModel

Imports System.Text

Imports System.Web

Imports System.Web.UI

Imports System.Web.UI.WebControls



Namespace WebControls



Public Enum en_TV_Resolution

PAL_160x120

PAL_320x240

PAL_352x288

PAL_352x576

PAL_480x576

PAL_720x576

PAL_768x608

End Enum



Public Enum en_ctrlITVcontent_ChildControlType

TextBox

DynamicTextBox

ImageButton

End Enum



<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissi
ons.SecurityAction.Demand, Name:="FullTrust")> _

Public Class ctrlITVcontent

Inherits WebControl

Implements IPostBackEventHandler

Implements INamingContainer

Public Event Click As EventHandler



Private myTVResolution As en_TV_Resolution

Private myCOL As New Collection







<Description("Gets or sets the original TV Resolution in Pixel."), _

Category("Layout"), _

DefaultValue(en_TV_Resolution.PAL_720x576)> _

Public Property OriginalTVResolution() As en_TV_Resolution

Get

Return myTVResolution

End Get

Set(ByVal Value As en_TV_Resolution)

myTVResolution = Value

End Set

End Property







Public Sub AddNewTextBox(ByVal PosX As Integer, ByVal PosY As Integer, ByVal
TVWidth As Integer, _

Optional ByVal InitText As String = "")

If TVWidth = 0 Then

Exit Sub

End If

Dim ctrl As New System.Web.UI.WebControls.TextBox

Dim css As String = "POSITION: absolute; "

Dim x As Integer = TVpx2PCpx_Width(PosX)

Dim y As Integer = TVpx2PCpx_Height(PosY)

Dim w As Integer = TVSize2PCSize_Width(TVWidth) 'TVpx2PCpx_Width(TVWidth)

css &= "LEFT: " & x.ToString & "px; "

css &= "TOP: " & y.ToString & "px;"

ctrl.Attributes.Add("style", css)

ctrl.Attributes.Add("width", w)

ctrl.Width = Unit.Pixel(w)

ctrl.Text = InitText

ctrl.ID = CreateID(en_ctrlITVcontent_ChildControlType.TextBox)

Me.Controls.Add(ctrl)

myCOL.Add(ctrl)

End Sub



Public Sub AddNewDynamicTextBox(ByVal PosX As Integer, ByVal PosY As
Integer, ByVal TVSize_W As Integer, _

' ...

' like "AddNewTextBox"

' ....

End Sub





Public Sub AddNewImageButton(ByVal PosX As Integer, ByVal PosY As Integer,
ByVal TVSize As Byte, _

ByVal PictureURL As String)

' ...

' like "AddNewTextBox"

' ...

End Sub



Public Sub RemoveAllChildControls()

If HasControls() Then

Dim i As Integer

For i = Controls.Count - 1 To 0 Step -1

Controls(i).Dispose()

Next

End If

End Sub



Private Function PAL_Width() As Integer

Select Case OriginalTVResolution

Case en_TV_Resolution.PAL_160x120 : Return 160

Case en_TV_Resolution.PAL_320x240 : Return 320

Case en_TV_Resolution.PAL_352x288 : Return 352

Case en_TV_Resolution.PAL_352x576 : Return 352

Case en_TV_Resolution.PAL_480x576 : Return 480

Case en_TV_Resolution.PAL_720x576 : Return 720

Case en_TV_Resolution.PAL_768x608 : Return 768

End Select

End Function



Private Function PAL_Height() As Integer

Select Case OriginalTVResolution

Case en_TV_Resolution.PAL_160x120 : Return 160

Case en_TV_Resolution.PAL_320x240 : Return 240

Case en_TV_Resolution.PAL_352x288 : Return 288

Case en_TV_Resolution.PAL_352x576 : Return 576

Case en_TV_Resolution.PAL_480x576 : Return 576

Case en_TV_Resolution.PAL_720x576 : Return 576

Case en_TV_Resolution.PAL_768x608 : Return 608

End Select

End Function



' size 1=1/1 2=1/2 4=1/4 8=1/8 des fernse-bildes (und sogleich in PC-Pixel
ummappen)

Private Function TVSize2PCSize_Width(ByVal TVSize As Integer) As Integer

Return TVpx2PCpx_Width(PAL_Width() * (1 / TVSize))

End Function

Private Function TVSize2PCSize_Height(ByVal TVSize As Integer) As Integer

Return TVpx2PCpx_Height(PAL_Height() * (1 / TVSize))

End Function

' PosX [tv] = 240 => wird in diesem Ctrl auf PosX [pc] = 166 gemappt

Private Function TVpx2PCpx_Width(ByVal TVPosX As Integer) As Integer

Return CInt(TVPosX / (PAL_Width() / Val(Me.Width.ToString)))

End Function

Private Function TVpx2PCpx_Height(ByVal TVPosY As Integer) As Integer

Return CInt(TVPosY / (PAL_Height() / Val(Me.Height.ToString)))

End Function



Private Function CreateID(ByVal ctrl_type As
en_ctrlITVcontent_ChildControlType) As String

Dim id_nr As Integer = Me.Controls.Count

Dim kz As String

Select Case ctrl_type

Case en_ctrlITVcontent_ChildControlType.TextBox : kz = "txtPreV" &
CStr(id_nr)

Case en_ctrlITVcontent_ChildControlType.DynamicTextBox : kz =
"txtCtrlPreView" & (id_nr)

Case en_ctrlITVcontent_ChildControlType.ImageButton : kz = "imgCtrlPreView"
& (id_nr)

End Select

Return kz

End Function



'Protected Overrides Sub AddAttributesToRender(ByVal writer As
System.Web.UI.HtmlTextWriter)

''


'End Sub



' invoke delegates registered with the click event.

Protected Overridable Sub OnClick(ByVal e As EventArgs)

RaiseEvent Click(Me, e)

End Sub

' raise click event to owner of this control

Public Sub RaisePostBackEvent(ByVal eventArgument As String) Implements
System.Web.UI.IPostBackEventHandler.RaisePostBackEvent

OnClick(New EventArgs)

End Sub



Protected Overrides Sub CreateChildControls()

Me.InitializeComponent()

End Sub



Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

MyBase.OnPreRender(e)

End Sub

Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)

Me.EnsureChildControls()

MyBase.Render(writer)

End Sub

Private Sub InitializeComponent()

If Me.Controls Is Nothing Then

Dim ctrl As Control

For Each ctrl In myCOL

Me.Controls.Add(ctrl)

Next

End If

End Sub





Private Sub EventHandler_ImageClicked(ByVal sender As Object, ByVal e As
System.Web.UI.ImageClickEventArgs)

Dim x As String

x = ""

End Sub



Private Sub EventHandler_DynamicTextChanged(ByVal sender As Object, ByVal e
As System.EventArgs)

Dim x As String

x = ""

End Sub



Protected Overrides Sub RenderChildren(ByVal writer As
System.Web.UI.HtmlTextWriter)

If HasControls() Then

Dim i As Integer

Dim c As New Control

For i = Controls.Count - 1 To 0 Step -1

Controls(i).RenderControl(writer)

Next

End If

End Sub

Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)

'

End Sub

End Class

End Namespace





############ CODE-END ############
Click to expand...
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Similar Threads

Persist viewstate in ITemplate child controls 0
Problems to serialize a Custom Collection Controls 0
Multiple control templates with the same control names 0
Problems Adding Dynamic Controls to Custom Web control 0
Rendering child controls "inline" 0
.net in run book help 0
Maintaining the look of dynamically added usercontrols 7
Accessing Properties of Custom Controls child Controls 8

Members online

No members online now.
Total: 64 (members: 1, guests: 63)
Robots: 439

Forum statistics

Threads
473,982
Messages
2,570,185
Members
46,736
Latest member
AdolphBig6

Latest Threads

Top