why does control remain visible after postback?

[Dan]

Hi,

i experimented with postback and viewstate. With this code, there are 2
dropdownlists created, one visible and with AutoPostBack true, the other not
visible and no AutoPostBack, and one button . The first time, when i choose
value "b" of DD1, the second DD appears. That's normal.

Now, what i don't understand is when i further click on the button (causing
a postback), the second DD remains visible. Don't think i don't want it. I
just don't uderstand.

After clicking the button, I thought the code would start from the very
begin, so setting DD2 again on not visible. And because the first DD1 has
not changed its selectedvalue, the procedure dropd changing DD2 into visible
will not be executed. So DD2 should stay invisible. But it's not.

Can somebody explain what's wrong in my way of thinking?
Thanks
Dan


Imports System.Collecti ons.Generic
Partial Class _Default
Inherits System.Web.UI.P age
Friend dds As New List(Of DropDownList)

Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
System.EventArg s) Handles Me.PreInit
Dim dd1, dd2 As DropDownList
Dim z1, z2 As ListItem
Dim lit As LiteralControl
If Not IsPostBack Then
dd1 = New DropDownList
dd1.ID = "dd1"
dd1.AutoPostBac k = True
z1 = New ListItem("a", "a")
dd1.Items.Add(z 1)
z1 = New ListItem("b", "b")
dd1.Items.Add(z 1)

dd2 = New DropDownList
dd2.ID = "dd2"
dd2.Visible = "false"
z2 = New ListItem("a", "a")
dd2.Items.Add(z 2)
z2 = New ListItem("b", "b")
dd2.Items.Add(z 2)

dds.Add(dd1)
dds.Add(dd2)
form1.Controls. Add(dd1)
form1.Controls. Add(dd2)
Session("dds") = dds
Else
dds = CType(Session(" dds"), List(Of DropDownList))
For Each d As DropDownList In dds
form1.Controls. Add(d)
Next
End If

Dim bt2 As New Button
form1.Controls. Add(bt2)
AddHandler bt2.Click, AddressOf submit_Click

For Each d As DropDownList In dds
AddHandler d.SelectedIndex Changed, AddressOf dropd
Next
End Sub

Protected Sub dropd(ByVal sender As Object, ByVal e As System.EventArg s)
Dim dd As DropDownList = CType(sender, DropDownList)
Session("sv" & dd.ID) = dd.SelectedValu e

If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = True
ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = False
End If
End Sub

Protected Sub submit_Click(By Val sender As Object, ByVal e As
System.EventArg s)

End Sub
End Class

[Joe Fawcett]

Re: why does control remain visible after postback?



"Dan" <d@ny.nlwrote in message
news:#VdOHHnvIH A.4376@TK2MSFTN GP06.phx.gbl...

Hi,
>
i experimented with postback and viewstate. With this code, there are 2
dropdownlists created, one visible and with AutoPostBack true, the other
not visible and no AutoPostBack, and one button . The first time, when i
choose value "b" of DD1, the second DD appears. That's normal.
>
Now, what i don't understand is when i further click on the button
(causing a postback), the second DD remains visible. Don't think i don't
want it. I just don't uderstand.
>
After clicking the button, I thought the code would start from the very
begin, so setting DD2 again on not visible. And because the first DD1 has
not changed its selectedvalue, the procedure dropd changing DD2 into
visible will not be executed. So DD2 should stay invisible. But it's not.
>
Can somebody explain what's wrong in my way of thinking?
Thanks
Dan
>
>
Imports System.Collecti ons.Generic
Partial Class _Default
Inherits System.Web.UI.P age
Friend dds As New List(Of DropDownList)
>
Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
System.EventArg s) Handles Me.PreInit
Dim dd1, dd2 As DropDownList
Dim z1, z2 As ListItem
Dim lit As LiteralControl
If Not IsPostBack Then
dd1 = New DropDownList
dd1.ID = "dd1"
dd1.AutoPostBac k = True
z1 = New ListItem("a", "a")
dd1.Items.Add(z 1)
z1 = New ListItem("b", "b")
dd1.Items.Add(z 1)
>
dd2 = New DropDownList
dd2.ID = "dd2"
dd2.Visible = "false"
z2 = New ListItem("a", "a")
dd2.Items.Add(z 2)
z2 = New ListItem("b", "b")
dd2.Items.Add(z 2)
>
dds.Add(dd1)
dds.Add(dd2)
form1.Controls. Add(dd1)
form1.Controls. Add(dd2)
Session("dds") = dds
Else
dds = CType(Session(" dds"), List(Of DropDownList))
For Each d As DropDownList In dds
form1.Controls. Add(d)
Next
End If
>
Dim bt2 As New Button
form1.Controls. Add(bt2)
AddHandler bt2.Click, AddressOf submit_Click
>
For Each d As DropDownList In dds
AddHandler d.SelectedIndex Changed, AddressOf dropd
Next
End Sub
>
Protected Sub dropd(ByVal sender As Object, ByVal e As
System.EventArg s)
Dim dd As DropDownList = CType(sender, DropDownList)
Session("sv" & dd.ID) = dd.SelectedValu e
>
If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = True
ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = False
End If
End Sub
>
Protected Sub submit_Click(By Val sender As Object, ByVal e As
System.EventArg s)
>
End Sub
End Class
>

The ViewState field maintains this sort of information, it then recreates
the controls after postback based on their previous state.

--

Joe Fawcett (MVP - XML)

http://joe.fawcett.name

[Dan]

Re: why does control remain visible after postback?

Hi, thanks for replying.

I put the property EnableViewState ="False"
but it makes no diffrerence: DD2 is still visible after clicking the button
....

Why?


"Joe Fawcett" <joefawcett@new sgroup.nospamsc hreef in bericht
news:CA1A3E19-D310-4123-899A-459577547F51@mi crosoft.com...

>
>
"Dan" <d@ny.nlwrote in message
news:#VdOHHnvIH A.4376@TK2MSFTN GP06.phx.gbl...

>Hi,
>>
>i experimented with postback and viewstate. With this code, there are 2
>dropdownlist s created, one visible and with AutoPostBack true, the other
>not visible and no AutoPostBack, and one button . The first time, when i
>choose value "b" of DD1, the second DD appears. That's normal.
>>
>Now, what i don't understand is when i further click on the button
>(causing a postback), the second DD remains visible. Don't think i don't
>want it. I just don't uderstand.
>>
>After clicking the button, I thought the code would start from the very
>begin, so setting DD2 again on not visible. And because the first DD1 has
>not changed its selectedvalue, the procedure dropd changing DD2 into
>visible will not be executed. So DD2 should stay invisible. But it's not.
>>
>Can somebody explain what's wrong in my way of thinking?
>Thanks
>Dan
>>
>>
>Imports System.Collecti ons.Generic
>Partial Class _Default
> Inherits System.Web.UI.P age
> Friend dds As New List(Of DropDownList)
>>
> Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
>System.EventAr gs) Handles Me.PreInit
> Dim dd1, dd2 As DropDownList
> Dim z1, z2 As ListItem
> Dim lit As LiteralControl
> If Not IsPostBack Then
> dd1 = New DropDownList
> dd1.ID = "dd1"
> dd1.AutoPostBac k = True
> z1 = New ListItem("a", "a")
> dd1.Items.Add(z 1)
> z1 = New ListItem("b", "b")
> dd1.Items.Add(z 1)
>>
> dd2 = New DropDownList
> dd2.ID = "dd2"
> dd2.Visible = "false"
> z2 = New ListItem("a", "a")
> dd2.Items.Add(z 2)
> z2 = New ListItem("b", "b")
> dd2.Items.Add(z 2)
>>
> dds.Add(dd1)
> dds.Add(dd2)
> form1.Controls. Add(dd1)
> form1.Controls. Add(dd2)
> Session("dds") = dds
> Else
> dds = CType(Session(" dds"), List(Of DropDownList))
> For Each d As DropDownList In dds
> form1.Controls. Add(d)
> Next
> End If
>>
> Dim bt2 As New Button
> form1.Controls. Add(bt2)
> AddHandler bt2.Click, AddressOf submit_Click
>>
> For Each d As DropDownList In dds
> AddHandler d.SelectedIndex Changed, AddressOf dropd
> Next
> End Sub
>>
> Protected Sub dropd(ByVal sender As Object, ByVal e As
>System.EventAr gs)
> Dim dd As DropDownList = CType(sender, DropDownList)
> Session("sv" & dd.ID) = dd.SelectedValu e
>>
> If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
> FindControl("dd 2").Visible = True
> ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
> FindControl("dd 2").Visible = False
> End If
> End Sub
>>
> Protected Sub submit_Click(By Val sender As Object, ByVal e As
>System.EventAr gs)
>>
> End Sub
>End Class
>>

The ViewState field maintains this sort of information, it then recreates
the controls after postback based on their previous state.
>
--
>
Joe Fawcett (MVP - XML)
http://joe.fawcett.name

[Dan]

Re: why does control remain visible after postback?

Joe?


"Dan" <d@ny.nlschre ef in bericht
news:OAZoDhpvIH A.5832@TK2MSFTN GP02.phx.gbl...

Hi, thanks for replying.
>
I put the property EnableViewState ="False"
but it makes no diffrerence: DD2 is still visible after clicking the
button ...
>
Why?
>
>
"Joe Fawcett" <joefawcett@new sgroup.nospamsc hreef in bericht
news:CA1A3E19-D310-4123-899A-459577547F51@mi crosoft.com...

>>
>>
>"Dan" <d@ny.nlwrote in message
>news:#VdOHHnvI HA.4376@TK2MSFT NGP06.phx.gbl.. .

>>Hi,
>>>
>>i experimented with postback and viewstate. With this code, there are 2
>>dropdownlis ts created, one visible and with AutoPostBack true, the other
>>not visible and no AutoPostBack, and one button . The first time, when i
>>choose value "b" of DD1, the second DD appears. That's normal.
>>>
>>Now, what i don't understand is when i further click on the button
>>(causing a postback), the second DD remains visible. Don't think i don't
>>want it. I just don't uderstand.
>>>
>>After clicking the button, I thought the code would start from the very
>>begin, so setting DD2 again on not visible. And because the first DD1
>>has not changed its selectedvalue, the procedure dropd changing DD2 into
>>visible will not be executed. So DD2 should stay invisible. But it's
>>not.
>>>
>>Can somebody explain what's wrong in my way of thinking?
>>Thanks
>>Dan
>>>
>>>
>>Imports System.Collecti ons.Generic
>>Partial Class _Default
>> Inherits System.Web.UI.P age
>> Friend dds As New List(Of DropDownList)
>>>
>> Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
>>System.EventA rgs) Handles Me.PreInit
>> Dim dd1, dd2 As DropDownList
>> Dim z1, z2 As ListItem
>> Dim lit As LiteralControl
>> If Not IsPostBack Then
>> dd1 = New DropDownList
>> dd1.ID = "dd1"
>> dd1.AutoPostBac k = True
>> z1 = New ListItem("a", "a")
>> dd1.Items.Add(z 1)
>> z1 = New ListItem("b", "b")
>> dd1.Items.Add(z 1)
>>>
>> dd2 = New DropDownList
>> dd2.ID = "dd2"
>> dd2.Visible = "false"
>> z2 = New ListItem("a", "a")
>> dd2.Items.Add(z 2)
>> z2 = New ListItem("b", "b")
>> dd2.Items.Add(z 2)
>>>
>> dds.Add(dd1)
>> dds.Add(dd2)
>> form1.Controls. Add(dd1)
>> form1.Controls. Add(dd2)
>> Session("dds") = dds
>> Else
>> dds = CType(Session(" dds"), List(Of DropDownList))
>> For Each d As DropDownList In dds
>> form1.Controls. Add(d)
>> Next
>> End If
>>>
>> Dim bt2 As New Button
>> form1.Controls. Add(bt2)
>> AddHandler bt2.Click, AddressOf submit_Click
>>>
>> For Each d As DropDownList In dds
>> AddHandler d.SelectedIndex Changed, AddressOf dropd
>> Next
>> End Sub
>>>
>> Protected Sub dropd(ByVal sender As Object, ByVal e As
>>System.EventA rgs)
>> Dim dd As DropDownList = CType(sender, DropDownList)
>> Session("sv" & dd.ID) = dd.SelectedValu e
>>>
>> If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
>> FindControl("dd 2").Visible = True
>> ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
>> FindControl("dd 2").Visible = False
>> End If
>> End Sub
>>>
>> Protected Sub submit_Click(By Val sender As Object, ByVal e As
>>System.EventA rgs)
>>>
>> End Sub
>>End Class
>>>

>The ViewState field maintains this sort of information, it then recreates
>the controls after postback based on their previous state.
>>
>--
>>
>Joe Fawcett (MVP - XML)
>http://joe.fawcett.name

>
>

[Joe Fawcett]

Re: why does control remain visible after postback?



"Dan" <d@ny.nlwrote in message
news:uJZngg0vIH A.420@TK2MSFTNG P02.phx.gbl...

Joe?
>
>
"Dan" <d@ny.nlschre ef in bericht
news:OAZoDhpvIH A.5832@TK2MSFTN GP02.phx.gbl...

>Hi, thanks for replying.
>>
>I put the property EnableViewState ="False"
>but it makes no diffrerence: DD2 is still visible after clicking the
>button ...
>>
>Why?
>>
>>
>"Joe Fawcett" <joefawcett@new sgroup.nospamsc hreef in bericht
>news:CA1A3E1 9-D310-4123-899A-459577547F51@mi crosoft.com...

>>>
>>>
>>"Dan" <d@ny.nlwrote in message
>>news:#VdOHHnv IHA.4376@TK2MSF TNGP06.phx.gbl. ..
>>>Hi,
>>>>
>>>i experimented with postback and viewstate. With this code, there are 2
>>>dropdownlist s created, one visible and with AutoPostBack true, the
>>>other not visible and no AutoPostBack, and one button . The first time,
>>>when i choose value "b" of DD1, the second DD appears. That's normal.
>>>>
>>>Now, what i don't understand is when i further click on the button
>>>(causing a postback), the second DD remains visible. Don't think i
>>>don't want it. I just don't uderstand.
>>>>
>>>After clicking the button, I thought the code would start from the very
>>>begin, so setting DD2 again on not visible. And because the first DD1
>>>has not changed its selectedvalue, the procedure dropd changing DD2
>>>into visible will not be executed. So DD2 should stay invisible. But
>>>it's not.
>>>>
>>>Can somebody explain what's wrong in my way of thinking?
>>>Thanks
>>>Dan
>>>>
>>>>
>>>Imports System.Collecti ons.Generic
>>>Partial Class _Default
>>> Inherits System.Web.UI.P age
>>> Friend dds As New List(Of DropDownList)
>>>>
>>> Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
>>>System.Event Args) Handles Me.PreInit
>>> Dim dd1, dd2 As DropDownList
>>> Dim z1, z2 As ListItem
>>> Dim lit As LiteralControl
>>> If Not IsPostBack Then
>>> dd1 = New DropDownList
>>> dd1.ID = "dd1"
>>> dd1.AutoPostBac k = True
>>> z1 = New ListItem("a", "a")
>>> dd1.Items.Add(z 1)
>>> z1 = New ListItem("b", "b")
>>> dd1.Items.Add(z 1)
>>>>
>>> dd2 = New DropDownList
>>> dd2.ID = "dd2"
>>> dd2.Visible = "false"
>>> z2 = New ListItem("a", "a")
>>> dd2.Items.Add(z 2)
>>> z2 = New ListItem("b", "b")
>>> dd2.Items.Add(z 2)
>>>>
>>> dds.Add(dd1)
>>> dds.Add(dd2)
>>> form1.Controls. Add(dd1)
>>> form1.Controls. Add(dd2)
>>> Session("dds") = dds
>>> Else
>>> dds = CType(Session(" dds"), List(Of DropDownList))
>>> For Each d As DropDownList In dds
>>> form1.Controls. Add(d)
>>> Next
>>> End If
>>>>
>>> Dim bt2 As New Button
>>> form1.Controls. Add(bt2)
>>> AddHandler bt2.Click, AddressOf submit_Click
>>>>
>>> For Each d As DropDownList In dds
>>> AddHandler d.SelectedIndex Changed, AddressOf dropd
>>> Next
>>> End Sub
>>>>
>>> Protected Sub dropd(ByVal sender As Object, ByVal e As
>>>System.Event Args)
>>> Dim dd As DropDownList = CType(sender, DropDownList)
>>> Session("sv" & dd.ID) = dd.SelectedValu e
>>>>
>>> If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
>>> FindControl("dd 2").Visible = True
>>> ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
>>> FindControl("dd 2").Visible = False
>>> End If
>>> End Sub
>>>>
>>> Protected Sub submit_Click(By Val sender As Object, ByVal e As
>>>System.Event Args)
>>>>
>>> End Sub
>>>End Class
>>>>
>>The ViewState field maintains this sort of information, it then
>>recreates the controls after postback based on their previous state.
>>>
>>--
>>>
>>Joe Fawcett (MVP - XML)
>>http://joe.fawcett.name

>>
>>

>
>

I tried to duplicate the situation but the second dropdown is not visible
after postback. The code is here:

TestViewState.a spx

<%@ Page Language="C#" AutoEventWireup ="true" CodeFile="Defau lt.aspx.cs"
Inherits="_Defa ult" %>

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

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Test ViewState</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownLi st ID="ddl1" runat="server" AutoPostBack="T rue"
Height="26px"
onselectedindex changed="ddl1_S electedIndexCha nged" Width="100px">
<asp:ListItem Selected="True" >a</asp:ListItem>
<asp:ListItem>b </asp:ListItem>
<asp:ListItem>c </asp:ListItem>
</asp:DropDownLis t>&nbsp;
<asp:DropDownLi st ID="ddl2" runat="server" EnableViewState ="False"
Height="31px" Visible="False" Width="100px">
<asp:ListItem Selected="True" >1</asp:ListItem>
<asp:ListItem>2 </asp:ListItem>
<asp:ListItem>3 </asp:ListItem>
</asp:DropDownLis t>&nbsp;<asp:Bu tton ID="cmd1" runat="server"
Text="Postback" />
</div>
</form>
</body>
</html>


TestViewState.a spx.cs
using System;

public partial class _Default : System.Web.UI.P age
{
protected void Page_Load(objec t sender, EventArgs e)
{

}
protected void ddl1_SelectedIn dexChanged(obje ct sender, EventArgs e)
{
if (ddl1.SelectedV alue.ToString() == "b")
ddl2.Visible = true;
else
ddl2.Visible = false;
}
}


--

Joe Fawcett (MVP - XML)

http://joe.fawcett.name

[Dan]

Re: why does control remain visible after postback?

Thanks again,

but there is a big difference between your code and mine: you define the
dropdownlists in the aspx file, i define everything in code-behind.

I certify that with this code below as it is, when both DDLs are visible and
when you then click on the submit button, both DDL remains visible.
And i tried with EnableViewState ="true" and with EnableViewState ="false".

Just copy and paste it in your IIS and try.

So i have still the same question: what makes that DDL remaining visible?

Imports System.Collecti ons.Generic
Partial Class _Default
Inherits System.Web.UI.P age
Friend dds As New List(Of DropDownList)

Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
System.EventArg s) Handles Me.PreInit
Dim dd1, dd2 As DropDownList
Dim z1, z2 As ListItem
If Not IsPostBack Then
dd1 = New DropDownList
dd1.ID = "dd1"
dd1.AutoPostBac k = True
z1 = New ListItem("a", "a")
dd1.Items.Add(z 1)
z1 = New ListItem("b", "b")
dd1.Items.Add(z 1)

dd2 = New DropDownList
dd2.ID = "dd2"
dd2.Visible = "false"
z2 = New ListItem("a", "a")
dd2.Items.Add(z 2)
z2 = New ListItem("b", "b")
dd2.Items.Add(z 2)

dds.Add(dd1)
dds.Add(dd2)
form1.Controls. Add(dd1)
form1.Controls. Add(dd2)
Session("dds") = dds
Else
dds = CType(Session(" dds"), List(Of DropDownList))
For Each d As DropDownList In dds
form1.Controls. Add(d)
Next
End If

Dim bt2 As New Button
form1.Controls. Add(bt2)
AddHandler bt2.Click, AddressOf submit_Click

For Each d As DropDownList In dds
AddHandler d.SelectedIndex Changed, AddressOf dropd
Next
End Sub

Protected Sub dropd(ByVal sender As Object, ByVal e As System.EventArg s)
Dim dd As DropDownList = CType(sender, DropDownList)
Session("sv" & dd.ID) = dd.SelectedValu e

If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = True
ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = False
End If
End Sub

Protected Sub submit_Click(By Val sender As Object, ByVal e As
System.EventArg s)
End Sub
End Class

----------------------------------------------------------------------------

[Lloyd Sheen]

Re: why does control remain visible after postback?


"Dan" <d@ny.nlwrote in message
news:OgDHfBDwIH A.2068@TK2MSFTN GP05.phx.gbl...

Thanks again,
>
but there is a big difference between your code and mine: you define the
dropdownlists in the aspx file, i define everything in code-behind.
>
I certify that with this code below as it is, when both DDLs are visible
and when you then click on the submit button, both DDL remains visible.
And i tried with EnableViewState ="true" and with EnableViewState ="false".
>
Just copy and paste it in your IIS and try.
>
So i have still the same question: what makes that DDL remaining visible?
>
Imports System.Collecti ons.Generic
Partial Class _Default
Inherits System.Web.UI.P age
Friend dds As New List(Of DropDownList)
>
Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
System.EventArg s) Handles Me.PreInit
Dim dd1, dd2 As DropDownList
Dim z1, z2 As ListItem
If Not IsPostBack Then
dd1 = New DropDownList
dd1.ID = "dd1"
dd1.AutoPostBac k = True
z1 = New ListItem("a", "a")
dd1.Items.Add(z 1)
z1 = New ListItem("b", "b")
dd1.Items.Add(z 1)
>
dd2 = New DropDownList
dd2.ID = "dd2"
dd2.Visible = "false"
z2 = New ListItem("a", "a")
dd2.Items.Add(z 2)
z2 = New ListItem("b", "b")
dd2.Items.Add(z 2)
>
dds.Add(dd1)
dds.Add(dd2)
form1.Controls. Add(dd1)
form1.Controls. Add(dd2)
Session("dds") = dds
Else
dds = CType(Session(" dds"), List(Of DropDownList))
For Each d As DropDownList In dds
form1.Controls. Add(d)
Next
End If
>
Dim bt2 As New Button
form1.Controls. Add(bt2)
AddHandler bt2.Click, AddressOf submit_Click
>
For Each d As DropDownList In dds
AddHandler d.SelectedIndex Changed, AddressOf dropd
Next
End Sub
>
Protected Sub dropd(ByVal sender As Object, ByVal e As
System.EventArg s)
Dim dd As DropDownList = CType(sender, DropDownList)
Session("sv" & dd.ID) = dd.SelectedValu e
>
If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = True
ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
FindControl("dd 2").Visible = False
End If
End Sub
>
Protected Sub submit_Click(By Val sender As Object, ByVal e As
System.EventArg s)
End Sub
End Class
>
----------------------------------------------------------------------------
>
>

You are not declaring the second drop down as AutoPostBack = True

Also if you turn Strict On ... (always a good thing to do to catch
problems), when you do you will see that you are trying to set a boolean to
"false". Those are the types of things that will bite you in the end.

Hope this helps
LS

[Dan]

Re: why does control remain visible after postback?

The second DDL has not its property AutoPostBack set on true, indeed, but
thus has nothing to do with the fact DD2 remains visibel after clicking the
submit button.

I tried the code with Strict on and off, but this makes no difference here
....

So, i still have the same question unsolved.
A great mystery in ASP.NET land or something stupid nobody sees?


"Lloyd Sheen" <a@b.cschreef in bericht
news:uUXb82DwIH A.5448@TK2MSFTN GP04.phx.gbl...

>
"Dan" <d@ny.nlwrote in message
news:OgDHfBDwIH A.2068@TK2MSFTN GP05.phx.gbl...

>Thanks again,
>>
>but there is a big difference between your code and mine: you define the
>dropdownlist s in the aspx file, i define everything in code-behind.
>>
>I certify that with this code below as it is, when both DDLs are visible
>and when you then click on the submit button, both DDL remains visible.
>And i tried with EnableViewState ="true" and with EnableViewState ="false".
>>
>Just copy and paste it in your IIS and try.
>>
>So i have still the same question: what makes that DDL remaining visible?
>>
>Imports System.Collecti ons.Generic
>Partial Class _Default
> Inherits System.Web.UI.P age
> Friend dds As New List(Of DropDownList)
>>
> Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
>System.EventAr gs) Handles Me.PreInit
> Dim dd1, dd2 As DropDownList
> Dim z1, z2 As ListItem
> If Not IsPostBack Then
> dd1 = New DropDownList
> dd1.ID = "dd1"
> dd1.AutoPostBac k = True
> z1 = New ListItem("a", "a")
> dd1.Items.Add(z 1)
> z1 = New ListItem("b", "b")
> dd1.Items.Add(z 1)
>>
> dd2 = New DropDownList
> dd2.ID = "dd2"
> dd2.Visible = "false"
> z2 = New ListItem("a", "a")
> dd2.Items.Add(z 2)
> z2 = New ListItem("b", "b")
> dd2.Items.Add(z 2)
>>
> dds.Add(dd1)
> dds.Add(dd2)
> form1.Controls. Add(dd1)
> form1.Controls. Add(dd2)
> Session("dds") = dds
> Else
> dds = CType(Session(" dds"), List(Of DropDownList))
> For Each d As DropDownList In dds
> form1.Controls. Add(d)
> Next
> End If
>>
> Dim bt2 As New Button
> form1.Controls. Add(bt2)
> AddHandler bt2.Click, AddressOf submit_Click
>>
> For Each d As DropDownList In dds
> AddHandler d.SelectedIndex Changed, AddressOf dropd
> Next
> End Sub
>>
> Protected Sub dropd(ByVal sender As Object, ByVal e As
>System.EventAr gs)
> Dim dd As DropDownList = CType(sender, DropDownList)
> Session("sv" & dd.ID) = dd.SelectedValu e
>>
> If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
> FindControl("dd 2").Visible = True
> ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
> FindControl("dd 2").Visible = False
> End If
> End Sub
>>
> Protected Sub submit_Click(By Val sender As Object, ByVal e As
>System.EventAr gs)
> End Sub
>End Class
>>
>----------------------------------------------------------------------------
>>
>>

>
You are not declaring the second drop down as AutoPostBack = True
>
Also if you turn Strict On ... (always a good thing to do to catch
problems), when you do you will see that you are trying to set a boolean
to "false". Those are the types of things that will bite you in the end.
>
Hope this helps
LS

[Nick Gilbert]

Re: why does control remain visible after postback?

Dan,

Out of interest, why are you defining all the controls programatically ?
Wouldn't it be much easier just to put them on the ASPX page and
show/hide them if you need to using the "visible" property?

It seems a very strange and complicated way to do what you're doing, but
I presume you have a good reason? :)

Nick..

Dan wrote:

The second DDL has not its property AutoPostBack set on true, indeed, but
thus has nothing to do with the fact DD2 remains visibel after clicking the
submit button.
>
I tried the code with Strict on and off, but this makes no difference here
...
>
So, i still have the same question unsolved.
A great mystery in ASP.NET land or something stupid nobody sees?
>
>
"Lloyd Sheen" <a@b.cschreef in bericht
news:uUXb82DwIH A.5448@TK2MSFTN GP04.phx.gbl...

>"Dan" <d@ny.nlwrote in message
>news:OgDHfBDwI HA.2068@TK2MSFT NGP05.phx.gbl.. .

>>Thanks again,
>>>
>>but there is a big difference between your code and mine: you define the
>>dropdownlis ts in the aspx file, i define everything in code-behind.
>>>
>>I certify that with this code below as it is, when both DDLs are visible
>>and when you then click on the submit button, both DDL remains visible.
>>And i tried with EnableViewState ="true" and with EnableViewState ="false".
>>>
>>Just copy and paste it in your IIS and try.
>>>
>>So i have still the same question: what makes that DDL remaining visible?
>>>
>>Imports System.Collecti ons.Generic
>>Partial Class _Default
>> Inherits System.Web.UI.P age
>> Friend dds As New List(Of DropDownList)
>>>
>> Protected Sub Page_PreInit(By Val sender As Object, ByVal e As
>>System.EventA rgs) Handles Me.PreInit
>> Dim dd1, dd2 As DropDownList
>> Dim z1, z2 As ListItem
>> If Not IsPostBack Then
>> dd1 = New DropDownList
>> dd1.ID = "dd1"
>> dd1.AutoPostBac k = True
>> z1 = New ListItem("a", "a")
>> dd1.Items.Add(z 1)
>> z1 = New ListItem("b", "b")
>> dd1.Items.Add(z 1)
>>>
>> dd2 = New DropDownList
>> dd2.ID = "dd2"
>> dd2.Visible = "false"
>> z2 = New ListItem("a", "a")
>> dd2.Items.Add(z 2)
>> z2 = New ListItem("b", "b")
>> dd2.Items.Add(z 2)
>>>
>> dds.Add(dd1)
>> dds.Add(dd2)
>> form1.Controls. Add(dd1)
>> form1.Controls. Add(dd2)
>> Session("dds") = dds
>> Else
>> dds = CType(Session(" dds"), List(Of DropDownList))
>> For Each d As DropDownList In dds
>> form1.Controls. Add(d)
>> Next
>> End If
>>>
>> Dim bt2 As New Button
>> form1.Controls. Add(bt2)
>> AddHandler bt2.Click, AddressOf submit_Click
>>>
>> For Each d As DropDownList In dds
>> AddHandler d.SelectedIndex Changed, AddressOf dropd
>> Next
>> End Sub
>>>
>> Protected Sub dropd(ByVal sender As Object, ByVal e As
>>System.EventA rgs)
>> Dim dd As DropDownList = CType(sender, DropDownList)
>> Session("sv" & dd.ID) = dd.SelectedValu e
>>>
>> If dd.ID = "dd1" And dd.SelectedValu e = "b" Then
>> FindControl("dd 2").Visible = True
>> ElseIf dd.ID = "dd1" And Not dd.SelectedValu e = "b" Then
>> FindControl("dd 2").Visible = False
>> End If
>> End Sub
>>>
>> Protected Sub submit_Click(By Val sender As Object, ByVal e As
>>System.EventA rgs)
>> End Sub
>>End Class
>>>
>>----------------------------------------------------------------------------
>>>
>>>

>You are not declaring the second drop down as AutoPostBack = True
>>
>Also if you turn Strict On ... (always a good thing to do to catch
>problems), when you do you will see that you are trying to set a boolean
>to "false". Those are the types of things that will bite you in the end.
>>
>Hope this helps
>LS

>
>