CheckedListBox forgets on TabControl

[Greg Burns]

I have a CheckedListBox on a TabControl's TabPage that cannot remeber which
items are checked when I switch between TabPages.

I had populated that CheckedListBox uses databinding, like so...

CheckedListBox1.DataSource = ds.Tables(0)
CheckedListBox1.DisplayMember = "FullName"
CheckedListBox1.ValueMember = "user_id"

I suspected the databinding had something to do with the control forgetting
what was checked. So I redesigned to manually loop through a DataReader and
add the items to it.

This presented the problem that I need to display "FullName", but use it
value "user_id". So I created a structure, structItem to accomplish this.

Structure structItem
Dim Display As String
Private m_Value As String
Shadows ReadOnly Property ToString()
Get
Return Display.ToString
End Get
End Property
Property Value()
Get
Return m_Value.Trim.ToString
End Get
Set(ByVal Value)
m_Value = Value
End Set
End Property
End Structure

Do While dr.Read
Dim MyItem As New structItem()

With MyItem
.Display = dr("FullName")
.Value = dr("user_id")
End With

With CheckedListBox1.Items
.Add(MyItem.Display.ToString, False)
End With
Loop

Now how to I get back my "Value" property when referencing the Checked item?
With databinding I used this code:

For i = 0 To CheckedListBox1.CheckedItems.Count - 1
MsgBox(CheckedListBox1.CheckedItems.Item(i)("user_id"))
Next

I've tried doing something like this, but it doesn't work:

For i = 0 To CheckedListBox1.CheckedItems.Count - 1
MsgBox(CType(CheckedListBox1.CheckedItems.Item(i), structItem).Value)
Next

Help!
Greg

[Steven Bras [MS]]

I would recommend using the following workaround to persist the checked
values, and leave the checked list box bound as you did first.

1. Add the following to set up a private array to hold the checked values
in the listbox:

Private oCheckedItems As DataRowView()

2. Prior to doing anything that will cause the listbox to become invisible,
save the state of the check boxes as follows:

ReDim oCheckedItems(CheckedListBox1.CheckedItems.Count - 1)
CheckedListBox1.CheckedItems.CopyTo(oCheckedItems, 0)

3. Just before the listbox becomes visible again (when user clicks the tab
containing the listbox), add the following code:

Dim x As Integer

For x = LBound(oCheckedItems) To UBound(oCheckedItems)
'Item(1) in the oCheckedItems(x) item is the display member; item(0)
would be the value member

CheckedListBox1.SetItemChecked(CheckedListBox1.FindStringExact(oCheckedItems
(x).Item(1).ToString, -1), True)
Next

This is clunky but may be useful if you find you cannot retrieve the data
from your structure.

Hope this helps!

Steven Bras, MCSD
Microsoft Developer Support/Visual Basic WebData

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[Greg Burns]

I don't seem to be the only experiencing this problem...
(http://groups.google.com/groups?hl=en&threadm=enhzxrncBHA.2680%40tkmsftngp0
7&rnum=24&prev=/groups%3Fq%3Dtabcontrol%2Bgroup:microsoft.public.dotnet.lang
uages.vb.*%26hl%3Den%26start%3D20%26sa%3DN)

Ideas?

Greg

[Greg Burns]

Thanks Steven, I will give it a shot.

Is this a bug, or by design? :)

Greg

"Steven Bras [MS]" <stev...@online.microsoft.com> wrote in message
news:v5jsOPt#BHA.2264@cpmsftngxa07...

[Greg Burns]

Here is part of the problem with my work-around code, I am adding just the
ToString result rather than MyItem structure.

Do While dr.Read
Dim MyItem As New structItem()

With MyItem
.Display = dr("FullName")
.Value = dr("user_id")
End With

With CheckedListBox1.Items
.Add(MyItem.Display.ToString, False) <<------
End With
Loop

But if I use this code...

With CheckedListBox1.Items
.Add(MyItem, False)
End With

It doesn't automatically display the result of ToString (like I was hoping),
instead it displays
"CheckedListBox.Form1+structItem"

grrr..

What is the benefit of being able to add any object type to a ListBox, if it
behaves like this? (In other words, what am I doing wrong!).

Greg

[Steven Bras [MS]]

This will be logged as a bug, but it's up to the development team how to
classify it. Sorry for the trouble it's caused!