problem with selectedvalue of dropdownlist

[Chris]

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value 'a'.
EnableViewState is by default set to true, so ... what's wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

[Lloyd Sheen]

"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value 'a'.
EnableViewState is by default set to true, so ... what's wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

You are recreating the dropdownlist every time you select an item. Since
you have AutoPostBack on you should be using a SelectionChanged routine to
pull the information from. Why are you creating the dropdown in code?

LS

[Rain]

Put your label setting code in the pre-render event or the index select
changed event for the dropdown box.


"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value 'a'.
EnableViewState is by default set to true, so ... what's wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

[Chris]

Thanks for replying.
I don't know in advance how many dropdownlists i need. This is coming from a
database, so i have to create them by code.
Doing like this, there is no SelectionChanged procedure available ...
"Lloyd Sheen" <[e-mail] in bericht
news:uV*************@TK2MSFTNGP02.phx.gbl...

>
"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

>Hi,

When choosing a value in the dropdownlist, i try to put that
selectedvalue in the label, but i always get the first value 'a'.
EnableViewState is by default set to true, so ... what's wrong in my
code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

You are recreating the dropdownlist every time you select an item. Since
you have AutoPostBack on you should be using a SelectionChanged routine to
pull the information from. Why are you creating the dropdown in code?

LS

[Rain]

Yes there is

You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is the
C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

public void myFunctionName( object sender, System.EventArgs e )


"Chris" <ss*@qsd.dcwrote in message
news:uM**************@TK2MSFTNGP02.phx.gbl...

Thanks for replying.
I don't know in advance how many dropdownlists i need. This is coming from
a database, so i have to create them by code.
Doing like this, there is no SelectionChanged procedure available ...
"Lloyd Sheen" <[e-mail] in bericht
news:uV*************@TK2MSFTNGP02.phx.gbl...

>>
"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

>>Hi,

When choosing a value in the dropdownlist, i try to put that
selectedvalue in the label, but i always get the first value 'a'.
EnableViewState is by default set to true, so ... what's wrong in my
code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

You are recreating the dropdownlist every time you select an item. Since
you have AutoPostBack on you should be using a SelectionChanged routine
to pull the information from. Why are you creating the dropdown in code?

LS

[Mark Rae [MVP]]

"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is the
C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to be
created in Page_Init or Page_PreInit - Page_Load is usually too late in the
page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Chris]

I resolved my problem like this:
Partial Class test
Inherits System.Web.UI.Page
Friend ddl As New DropDownList
Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load

Dim z As ListItem
Dim kz As String
If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
End If
End Sub

Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit
ddl.AutoPostBack = True
form1.Controls.Add(ddl)
End Sub
End Class
Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit
ddl.AutoPostBack = True
form1.Controls.Add(ddl)
End Sub

But this generates a new problem to me: how can i program that in code?
Assume i need 5 dropdownlists: i can create dim ddl() and then redim
ddl(number needed). But how to do that with Friend, which must be outside
all sub? Or is there a better way to do this?


"Mark Rae [MVP]" <ma**@markNOSPAMrae.netschreef in bericht
news:%2****************@TK2MSFTNGP03.phx.gbl...

"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

>You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is
the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to
be created in Page_Init or Page_PreInit - Page_Load is usually too late in
the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Chris]

or maybe better, but still same problem: how to code all the Friend
variables i need ..

Partial Class test
Inherits System.Web.UI.Page
Friend ddl As New DropDownList

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim z As ListItem
If Not Page.IsPostBack Then
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
End If
End Sub

Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit
ddl.AutoPostBack = True
form1.Controls.Add(ddl)
AddHandler ddl.SelectedIndexChanged, AddressOf selectddl
End Sub
Protected Sub selectddl(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim kz As String
kz = ddl.SelectedValue
Label1.Text = kz
End Sub
End Class

"Chris" <ss*@qsd.dcschreef in bericht
news:us**************@TK2MSFTNGP03.phx.gbl...

>I resolved my problem like this:
Partial Class test
Inherits System.Web.UI.Page
Friend ddl As New DropDownList
Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load

Dim z As ListItem
Dim kz As String
If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
End If
End Sub

Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit
ddl.AutoPostBack = True
form1.Controls.Add(ddl)
End Sub
End Class
Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit
ddl.AutoPostBack = True
form1.Controls.Add(ddl)
End Sub

But this generates a new problem to me: how can i program that in code?
Assume i need 5 dropdownlists: i can create dim ddl() and then redim
ddl(number needed). But how to do that with Friend, which must be outside
all sub? Or is there a better way to do this?


"Mark Rae [MVP]" <ma**@markNOSPAMrae.netschreef in bericht
news:%2****************@TK2MSFTNGP03.phx.gbl...

>"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

>>You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is
the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to
be created in Page_Init or Page_PreInit - Page_Load is usually too late
in the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Rain]

Where did I mention doing it in the Page_Load ?
"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl...

"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

>You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is
the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to
be created in Page_Init or Page_PreInit - Page_Load is usually too late in
the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Chris]

I don't know ...
If you really want to help, please just tell me what's wrong
Thanks
"Rain" <[e-mail] in bericht
news:%2****************@TK2MSFTNGP04.phx.gbl...

Where did I mention doing it in the Page_Load ?
"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl...

>"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

>>You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is
the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to
be created in Page_Init or Page_PreInit - Page_Load is usually too late
in the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Mark Rae [MVP]]

"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

[top-posting corrected]

>>You can create an event handler to service the event. Have a look in the
help for adding event handlers. Its a fairly simple one to do. This is
the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need to
be created in Page_Init or Page_PreInit - Page_Load is usually too late
in the page cycle...

Where did I mention doing it in the Page_Load ?

You didn't - that's how it was in the OP's code...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Mark Rae [MVP]]

"Chris" <ss*@qsd.dcwrote in message
news:us**************@TK2MSFTNGP03.phx.gbl...

But this generates a new problem to me: how can i program that in code?
Assume i need 5 dropdownlists: i can create dim ddl() and then redim
ddl(number needed). But how to do that with Friend, which must be outside
all sub? Or is there a better way to do this?

I think you're making life difficult for yourself...

In Pre_Init, work out how many dynamic DropDownLists you need and simply add
them to the webform's control collection...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Rain]

Cool, I didnt think I had

;-)

Cheers
"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:e7**************@TK2MSFTNGP04.phx.gbl...

"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl...

[top-posting corrected]

>>>You can create an event handler to service the event. Have a look in
the help for adding event handlers. Its a fairly simple one to do. This
is the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need
to be created in Page_Init or Page_PreInit - Page_Load is usually too
late in the page cycle...

Where did I mention doing it in the Page_Load ?

You didn't - that's how it was in the OP's code...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Rain]

This works ( tested ) , hopefully it will help you in formulating your
solution.

--------------------
Private ddls As New ArrayList
Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit

If (Not IsPostBack) Then
Dim myFirstDDl As New DropDownList
myFirstDDl.Items.Add(New ListItem("a", "a"))
myFirstDDl.Items.Add(New ListItem("b", "b"))
myFirstDDl.Items.Add(New ListItem("c", "c"))
myFirstDDl.AutoPostBack = True
'add to ddls array list
ddls.Add(myFirstDDl)

'Save between postbacks
Session("ddls") = ddls
Else
'retreive on postback
ddls = CType(Session("ddls"), ArrayList)

End If

For Each d As DropDownList In ddls

'add to page controls
form1.Controls.Add(d)
AddHandler d.SelectedIndexChanged, AddressOf
handleDDlIndexChanged
Next
End Sub

Protected Sub handleDDlIndexChanged(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim ddl As DropDownList = CType(sender, DropDownList)

Label1.Text = ddl.SelectedValue

End Sub




-----------------------------------------------
"Chris" <ss*@qsd.dcwrote in message
news:eM**************@TK2MSFTNGP03.phx.gbl...

>I don't know ...
If you really want to help, please just tell me what's wrong
Thanks
"Rain" <[e-mail] in bericht
news:%2****************@TK2MSFTNGP04.phx.gbl...

>Where did I mention doing it in the Page_Load ?
"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl...

>>"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl.. .

You can create an event handler to service the event. Have a look in
the help for adding event handlers. Its a fairly simple one to do. This
is the C# equiv, ( For VB lookup the Addhandler in help ).

this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need
to be created in Page_Init or Page_PreInit - Page_Load is usually too
late in the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Mark Rae [MVP]]

"Rain" <[e-mail] in message
news:eT**************@TK2MSFTNGP06.phx.gbl...

*** [top-posting corrected again] ***

>>Where did I mention doing it in the Page_Load ?

You didn't - that's how it was in the OP's code...

Cool, I didnt think I had

No problem.
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Chris]

Many thanks.
"Rain" <[e-mail] in bericht
news:%2****************@TK2MSFTNGP04.phx.gbl...

This works ( tested ) , hopefully it will help you in formulating your
solution.

--------------------
Private ddls As New ArrayList
Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.PreInit

If (Not IsPostBack) Then
Dim myFirstDDl As New DropDownList
myFirstDDl.Items.Add(New ListItem("a", "a"))
myFirstDDl.Items.Add(New ListItem("b", "b"))
myFirstDDl.Items.Add(New ListItem("c", "c"))
myFirstDDl.AutoPostBack = True
'add to ddls array list
ddls.Add(myFirstDDl)

'Save between postbacks
Session("ddls") = ddls
Else
'retreive on postback
ddls = CType(Session("ddls"), ArrayList)

End If

For Each d As DropDownList In ddls

'add to page controls
form1.Controls.Add(d)
AddHandler d.SelectedIndexChanged, AddressOf
handleDDlIndexChanged
Next
End Sub

Protected Sub handleDDlIndexChanged(ByVal sender As Object, ByVal e As
System.EventArgs)
Dim ddl As DropDownList = CType(sender, DropDownList)

Label1.Text = ddl.SelectedValue

End Sub




-----------------------------------------------
"Chris" <ss*@qsd.dcwrote in message
news:eM**************@TK2MSFTNGP03.phx.gbl...

>>I don't know ...
If you really want to help, please just tell me what's wrong
Thanks
"Rain" <[e-mail] in bericht
news:%2****************@TK2MSFTNGP04.phx.gbl...

>>Where did I mention doing it in the Page_Load ?
"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl.. .
"Rain" <[e-mail] in message
news:%2****************@TK2MSFTNGP04.phx.gbl. ..

You can create an event handler to service the event. Have a look in
the help for adding event handlers. Its a fairly simple one to do.
This is the C# equiv, ( For VB lookup the Addhandler in help ).
>
this.DropDownList1.SelectedIndexChanged += new
System.EventHandler(myFunctionName);

Remember that dynamic controls which need to have events wired up need
to be created in Page_Init or Page_PreInit - Page_Load is usually too
late in the page cycle...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net