HELP with ASP.NET DropDownList Box ! : )

  • Thread starter Thread starter Lucas Tam
  • Start date Start date
L

Lucas Tam

Hi all,

I have a DropDownList on my page created in Design Time calledddlDate. In
code, I do the following:

1 ddlDate = New DropDownList() <- To Clear the drop down list
2 ddlDate.Items.Add("HELLO")
3 ddlDate.Items.Add("WORLD")

When the page loads, how come my drop downlist is empty? Shouldn't there be
two entries?

If I remove Line 1, then the entries are present. However, logically
speaking, why does Line 1 mess things up?

Thanks!
 
This has worked for me beforfe, but its IE only I think

Dim EncodedString As String = "This is a Test
String"    EndTestString"
Dim writer As New System.IO.StringWriter()
Server.HtmlDecode(EncodedString, writer)
Dim DecodedString As String = writer.ToString()
lstTest.Items.Add(DecodedString)

--
Regards

John Timney (Microsoft ASP.NET MVP)
----------------------------------------------
<shameless_author_plug>
Professional .NET for Java Developers with C#
ISBN:1-861007-91-4
Professional Windows Forms
ISBN: 1861005547
Professional JSP 2nd Edition
ISBN: 1861004958
Professional JSP
ISBN: 1861003625
Beginning JSP Web Development
ISBN: 1861002092
</shameless_author_plug>
 
Lucas,

You say you are creating the drop down list dynamically. It sounds like you
are creating the entries in the drop down dynamically, but that the list was
added to the page in the design window.

If this is the case then the drop down you are creating (the new one) is
replacing the one in the design window and you aren't setting most of it's
attributes.

If it is the case that you have added the drop down to the page via the
design window then instead of using "New" to clear the drop down do it like
this:

ddlDate.Items.Clear()

Sincerely,

--
S. Justin Gengo, MCP
Web Developer

Free code library at:
www.aboutfortunate.com

"Out of chaos comes order."
Nietzche
 
If this is the case then the drop down you are creating (the new one)
is replacing the one in the design window and you aren't setting most
of it's attributes.
Click to expand...

Yes exactly! That is what I am doing.

If it is the case that you have added the drop down to the page via
the design window then instead of using "New" to clear the drop down
do it like this:

ddlDate.Items.Clear()
Click to expand...

However, shouldn't using New() to clear also work? Logically speaking,
shouldn't new() bind a new instance to the control? I wonder why it won't
pick up the newly bound control.

BTW, your suggestion worked great! Thanks for your help!
 
Lucas,

It's because other settings are defined by the page.

Take a look in the web for designer generated code area of the codebehind
page.

You'll see the following:

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

The routine above actually runs setup routines for the components on your
page. When you called "New" you overwrote all those "Hidden" settings. If
declare a new component you have to recreate them.

Sincerely,

--
S. Justin Gengo, MCP
Web Developer

Free code library at:
www.aboutfortunate.com

"Out of chaos comes order."
Nietzche
 
sorry Lucas, I appear to have replied to the wrong post here

--
Regards

John Timney (Microsoft ASP.NET MVP)
----------------------------------------------
<shameless_author_plug>
Professional .NET for Java Developers with C#
ISBN:1-861007-91-4
Professional Windows Forms
ISBN: 1861005547
Professional JSP 2nd Edition
ISBN: 1861004958
Professional JSP
ISBN: 1861003625
Beginning JSP Web Development
ISBN: 1861002092
</shameless_author_plug>
----------------------------------------------

John Timney (Microsoft MVP) said:
This has worked for me beforfe, but its IE only I think

Dim EncodedString As String = "This is a Test
String"    EndTestString"
Dim writer As New System.IO.StringWriter()
Server.HtmlDecode(EncodedString, writer)
Dim DecodedString As String = writer.ToString()
lstTest.Items.Add(DecodedString)

--
Regards

John Timney (Microsoft ASP.NET MVP)
----------------------------------------------
<shameless_author_plug>
Professional .NET for Java Developers with C#
ISBN:1-861007-91-4
Professional Windows Forms
ISBN: 1861005547
Professional JSP 2nd Edition
ISBN: 1861004958
Professional JSP
ISBN: 1861003625
Beginning JSP Web Development
ISBN: 1861002092
</shameless_author_plug>
----------------------------------------------
Click to expand...
 
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