ComboBox's SelectedIndex Property problem

[Eric A. Johnson]

Hi Everyone,

I am at my wit's end here. I have a combobox (combyQueryTitl e) that I
need to use in order to select a query for my database project. Therefore,
I am using the comboQueryTitle _SelectedIndexC hanged handler to, when a new
selection is made, update the query and refresh the display. The only
problem is that the program seems to inexplicably start with the
..selectedindex property at -1! This makes no sense to me. Furthermore,
this is, apparently, happening *before* my form loads, as not only does the
form not appear on screen, but even when I put a breakpoint at the first
possible line within the form_load handler, it still crashes; the breakpoint
is never even reached. Is there a way to locate the point at which the
property is being changed to (or created with) the value of -1? It seems to
me that it should not happen at all.
Please respond here, if possible; if you need more info, you can reach
me via AIM at ajeric74. Thank you!

-- Eric

[Qwert]

Re: ComboBox's SelectedIndex Property problem

Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
Then cmbComboBox.Sel ectedIndex is -1 (default value)

You get an error if you would try this:
Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
cmbComboBox.Sel ectedIndex = 0

Can't you exit event _SelectedIndexC hanged when the index is invalid?

With cmbComboBox
If .SelectedIndex < 0 Or .SelectedIndex >= .Items.Count Then
Exit Sub
End If
End With


"Eric A. Johnson" <nothere@dontlo okforme.com> schreef in bericht
news:7Q_4f.1722 4$6e1.7021@news svr14.news.prod igy.com...[color=blue]
> Hi Everyone,
>
> I am at my wit's end here. I have a combobox (combyQueryTitl e) that I
> need to use in order to select a query for my database project.
> Therefore,
> I am using the comboQueryTitle _SelectedIndexC hanged handler to, when a new
> selection is made, update the query and refresh the display. The only
> problem is that the program seems to inexplicably start with the
> .selectedindex property at -1! This makes no sense to me. Furthermore,
> this is, apparently, happening *before* my form loads, as not only does
> the
> form not appear on screen, but even when I put a breakpoint at the first
> possible line within the form_load handler, it still crashes; the
> breakpoint
> is never even reached. Is there a way to locate the point at which the
> property is being changed to (or created with) the value of -1? It seems
> to
> me that it should not happen at all.
> Please respond here, if possible; if you need more info, you can reach
> me via AIM at ajeric74. Thank you!
>
> -- Eric
>
>[/color]

[Boo K.M.]

Re: ComboBox's SelectedIndex Property problem


"Qwert" <nosp@nosp.co m> wrote in message
news:WcmdncnKMp RmB8neRVnyrA@ca sema.nl...[color=blue]
> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
> Then cmbComboBox.Sel ectedIndex is -1 (default value)
>
> You get an error if you would try this:
> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
> cmbComboBox.Sel ectedIndex = 0
>
> Can't you exit event _SelectedIndexC hanged when the index is invalid?
>
> With cmbComboBox
> If .SelectedIndex < 0 Or .SelectedIndex >= .Items.Count Then
> Exit Sub
> End If
> End With
>
>[/color]

I would like to ask for a side question.
If that is -1 (by default), how do I set the combo text when there is no
selection? Something like web pages "(Please choose a category from
list)"...

That will help a lot. TIA.

Boo K.M.

[ECathell]

Re: ComboBox's SelectedIndex Property problem

Better form would be

If not me.cmbComboBox. selectedindex=-1 then
'do something
end if

put that inside your handler....


--
--Eric Cathell, MCSA
"Qwert" <nosp@nosp.co m> wrote in message
news:WcmdncnKMp RmB8neRVnyrA@ca sema.nl...[color=blue]
> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
> Then cmbComboBox.Sel ectedIndex is -1 (default value)
>
> You get an error if you would try this:
> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
> cmbComboBox.Sel ectedIndex = 0
>
> Can't you exit event _SelectedIndexC hanged when the index is invalid?
>
> With cmbComboBox
> If .SelectedIndex < 0 Or .SelectedIndex >= .Items.Count Then
> Exit Sub
> End If
> End With
>
>
> "Eric A. Johnson" <nothere@dontlo okforme.com> schreef in bericht
> news:7Q_4f.1722 4$6e1.7021@news svr14.news.prod igy.com...[color=green]
>> Hi Everyone,
>>
>> I am at my wit's end here. I have a combobox (combyQueryTitl e) that I
>> need to use in order to select a query for my database project.
>> Therefore,
>> I am using the comboQueryTitle _SelectedIndexC hanged handler to, when a
>> new
>> selection is made, update the query and refresh the display. The only
>> problem is that the program seems to inexplicably start with the
>> .selectedindex property at -1! This makes no sense to me. Furthermore,
>> this is, apparently, happening *before* my form loads, as not only does
>> the
>> form not appear on screen, but even when I put a breakpoint at the first
>> possible line within the form_load handler, it still crashes; the
>> breakpoint
>> is never even reached. Is there a way to locate the point at which the
>> property is being changed to (or created with) the value of -1? It seems
>> to
>> me that it should not happen at all.
>> Please respond here, if possible; if you need more info, you can reach
>> me via AIM at ajeric74. Thank you!
>>
>> -- Eric
>>
>>[/color]
>
>[/color]

[ECathell]

Re: ComboBox's SelectedIndex Property problem

Hard code that as your first selection. Then when you bind the datasource it
should fill in under that selection.

-1 means the control is initializing or is stateless(I think I read that on
MSDN) Once the form is loaded the default index=0

combo box's can be a pain....


--
--Eric Cathell, MCSA
"Boo K.M." <boo_k.m.NOSPAM @bkm-researcher.com> wrote in message
news:4354b819_2 @news.tm.net.my ...[color=blue]
>
> "Qwert" <nosp@nosp.co m> wrote in message
> news:WcmdncnKMp RmB8neRVnyrA@ca sema.nl...[color=green]
>> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
>> Then cmbComboBox.Sel ectedIndex is -1 (default value)
>>
>> You get an error if you would try this:
>> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
>> cmbComboBox.Sel ectedIndex = 0
>>
>> Can't you exit event _SelectedIndexC hanged when the index is invalid?
>>
>> With cmbComboBox
>> If .SelectedIndex < 0 Or .SelectedIndex >= .Items.Count Then
>> Exit Sub
>> End If
>> End With
>>
>>[/color]
>
> I would like to ask for a side question.
> If that is -1 (by default), how do I set the combo text when there is no
> selection? Something like web pages "(Please choose a category from
> list)"...
>
> That will help a lot. TIA.
>
> Boo K.M.
>[/color]

[ECathell]

Re: ComboBox's SelectedIndex Property problem

I think you actually want to use .text value. Actually you can databind the
same combobox to 2 different datasources. So if you have a table that has
the query name, query you could do something like this

cbo.datasource= table
cbo.diplaymembe r=column0name
cbo.databinding .add(new binding("text", table,"column0n ame)
cbo.databinding .add(new binding("valuem ember",table,"c olumn1name)

then you would be able to get the querystring off the .selectedvalue
property.

Play around with it some, I ALWAYS have to tinker with my comboboxes because
it always seems each situation needs a different approach. Combos are a
pain...but thats because they are very powerful.


--
--Eric Cathell, MCSA
"Eric A. Johnson" <nothere@dontlo okforme.com> wrote in message
news:g%k5f.1741 8$6e1.5498@news svr14.news.prod igy.com...[color=blue]
> As a matter of fact, is it possible to get the text associated with an
> index within the combobox without actually modifying the .selectedindex
> property? It is extremely annoying, trying to change within the program
> code the selected index, only to have it crash because... I don't even
> know why. I can't understand why it won't allow me to change the selected
> index! The tooltip in VB.NET tells me that the .selectedindex method
> allows me to get or set the index that is selected. Maybe if someone can
> point me to a detailed explanation of this idiotic behavior and how to
> work around it? I just want the invisible combobox's index to be the same
> as the visible one. My AIM name is ajeric74... SOMEBODY please come online
> to help me!!!
>
> -- Eric
>
> "Eric A. Johnson" <nothere@dontlo okforme.com> wrote in message
> news:vMk5f.1741 5$6e1.185@newss vr14.news.prodi gy.com...[color=green]
>> Okay, I have another question: What I'm trying to do is to use an
>> ordinary combobox to hold the query title, and an invisible combobox to
>> hold the actual query. I want to make it so that the invisible combobox
>> will change to match the visible one, thereby allowing its .text property
>> to contain the proper query. Is that possible?
>>
>> TIA,
>> Eric
>>
>> "ECathell" <ecathell@nospa m.com> wrote in message
>> news:Ogobw0%230 FHA.1564@tk2msf tngp13.phx.gbl. ..[color=darkred]
>>> Better form would be
>>>
>>> If not me.cmbComboBox. selectedindex=-1 then
>>> 'do something
>>> end if
>>>
>>> put that inside your handler....
>>>
>>>
>>> --
>>> --Eric Cathell, MCSA
>>> "Qwert" <nosp@nosp.co m> wrote in message
>>> news:WcmdncnKMp RmB8neRVnyrA@ca sema.nl...
>>>> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
>>>> Then cmbComboBox.Sel ectedIndex is -1 (default value)
>>>>
>>>> You get an error if you would try this:
>>>> Me.cmbComboBox= New System.Windows. Forms.ComboBox( )
>>>> cmbComboBox.Sel ectedIndex = 0
>>>>
>>>> Can't you exit event _SelectedIndexC hanged when the index is invalid?
>>>>
>>>> With cmbComboBox
>>>> If .SelectedIndex < 0 Or .SelectedIndex >= .Items.Count Then
>>>> Exit Sub
>>>> End If
>>>> End With
>>>>
>>>>
>>>> "Eric A. Johnson" <nothere@dontlo okforme.com> schreef in bericht
>>>> news:7Q_4f.1722 4$6e1.7021@news svr14.news.prod igy.com...
>>>>> Hi Everyone,
>>>>>
>>>>> I am at my wit's end here. I have a combobox (combyQueryTitl e)
>>>>> that I
>>>>> need to use in order to select a query for my database project.
>>>>> Therefore,
>>>>> I am using the comboQueryTitle _SelectedIndexC hanged handler to, when a
>>>>> new
>>>>> selection is made, update the query and refresh the display. The only
>>>>> problem is that the program seems to inexplicably start with the
>>>>> .selectedindex property at -1! This makes no sense to me.
>>>>> Furthermore,
>>>>> this is, apparently, happening *before* my form loads, as not only
>>>>> does the
>>>>> form not appear on screen, but even when I put a breakpoint at the
>>>>> first
>>>>> possible line within the form_load handler, it still crashes; the
>>>>> breakpoint
>>>>> is never even reached. Is there a way to locate the point at which
>>>>> the
>>>>> property is being changed to (or created with) the value of -1? It
>>>>> seems to
>>>>> me that it should not happen at all.
>>>>> Please respond here, if possible; if you need more info, you can
>>>>> reach
>>>>> me via AIM at ajeric74. Thank you!
>>>>>
>>>>> -- Eric
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>[/color]
>>
>>[/color]
>
>[/color]