Now THIS is a weird problem! [Resolved]

**mendhak** · Jun 23rd, 2004, 04:48 AM

The problem is simple, the text is long.

For this problem, I'll need you to actually download the attached ZIP file. It's VB.NET source code, so yeah, go ahead and look at it before you run it. It works with the Northwind database, so you shouldn't have any problems there.

It consists of a form1.vb, and a class1.vb.

First, the problem:

Load up the form. It'll load everything, listbox, combo boxes, textboxes, everything.

Now, you'll have the first record loaded up: Product "Chai" (btw, that's the Persian word for Tea)

Without editing anything, press the update button, and watch the Supplier's combobox change value! The Category combobox does not, even though I'm using the same technique to udpate them.

Also, you'll notice that the form's title has changed to the .SelectedIndex of the combobox.

Press Update again.

it's just going to keep changing. It goes in a very weird loop.

If I use a rougher technique to do the update it works fine. (which you will find commented out underneath the actual line being used)

Can someone take a look? It's absolutely baffling.

**mendhak** · Jun 23rd, 2004, 05:00 AM

Sorry, the commented line is not in the ZIP file.

Here it is, the first line has to be replaced with the second line, and it'll start working properly.

VB Code:

'dr("SupplierID") = CType(cboSupplier.SelectedItem, ListItemNumeric).ID
        dr("SupplierID") = CInt(cboSupplier.SelectedIndex + 1)

**Magiaus** · Jun 23rd, 2004, 06:43 AM

You put the joint out and it came to you right?

**mendhak** · Jun 23rd, 2004, 07:05 AM

Nah, that joint's been permanently welded to my fingers.

Any idea why I'm getting that odd problem?

**Magiaus** · Jun 23rd, 2004, 11:25 AM

nope. I haven't done anything like that yet. If I get time today I'll check it out though.

**Wokawidget** · Jun 24th, 2004, 04:35 AM

Originally posted by mendhak
Sorry, the commented line is not in the ZIP file.

Here it is, the first line has to be replaced with the second line, and it'll start working properly.

VB Code:

'dr("SupplierID") = CType(cboSupplier.SelectedItem, ListItemNumeric).ID
dr("SupplierID") = CInt(cboSupplier.SelectedIndex + 1)

Hmmm...bad code.
That's basing it on the fact that the 1st index in the DB is 1 and that NON are missing. What if the index goes 1,2,3,7,14,23,24,25...your selectedindex won't work.

What on earth is the purpose of your class1 (ListItemNumeric)???!!!

Wpopooof

**mendhak** · Jun 24th, 2004, 05:03 AM

Originally posted by Wokawidget
Hmmm...bad code.
That's basing it on the fact that the 1st index in the DB is 1 and that NON are missing. What if the index goes 1,2,3,7,14,23,24,25...your selectedindex won't work.

What on earth is the purpose of your class1 (ListItemNumeric)???!!!

Wpopooof

That is not the issue, what I've shown here is a very crude workaround. THeoretically, I should not be having to resort to such a technique, and be using the commented line instead. But it just doesn't work.

ListItemNumeric is a class I wrote that can hold a Value and an ID, so that I can populate my listbox with a bunch of ListItemNumeric objects that have a displayed value, and an underlying ID, and that takes care of the situation you mentioned, where the IDs are not in an order.

The line:

VB Code:

CType(cboSupplier.SelectedItem, ListItemNumeric).ID

takes the currently selected item in the listbox, and gets the ID out.

Good?

**mendhak** · Jun 24th, 2004, 05:04 AM

Btw, did you run the sample? Are you seeing the same problem as I mentioned?

**Wokawidget** · Jun 24th, 2004, 05:05 AM

Yes and yes. I am still failing to see why you are using a class...???
Woof

**mendhak** · Jun 24th, 2004, 05:12 AM

Originally posted by Wokawidget
Yes and yes. I am still failing to see why you are using a class...???
Woof

I'll try to explain:

As you're seeing, the listbox on the left has a lot of values in it. Now everytime you click on another item in the listbox, the values in the textboxes and comboboxes change. For this, the database needs to be requeried each time.

And most logically, to query the database for the values corresponding to any particular item in the listbox, we need a Primary Key, correct?

I needed a place to store the primary key. So, since the listbox actually accepts objects, I declared a class that would hold a .VALUE property (which is what you are seeing, "Chai") and a .ID property (which you don't see), used when querying.

Try to think of another way to do this same thing, you'll find that this is an ideal way to do it.

In my opinion at least. I'm new to VB.NET, so it's possible that there is a better way. So far, I don't see a better way.

Comprende vous, smelly badger?
*SLAP*

**Wokawidget** · Jun 24th, 2004, 05:26 AM

Well, your problem is not with the saving...IT'S WITH THE LOADING

damn caps

**Wokawidget** · Jun 24th, 2004, 05:33 AM

You muppet!
You are saving the CORRECT ID's to the DB...but when you load them you are treating the ID as the LISTINDEX!

Hahahaha

VB Code:

Private Sub FindItem(ByVal cboName As ComboBox, ByVal strID As String)
 
 
        Try
            cboName.SelectedIndex = CInt(strID) - 1
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try
 
 
 
 
    End Sub

Wrong wrong wrong

Woof

**mendhak** · Jun 24th, 2004, 05:36 AM

Originally posted by Wokawidget
You muppet!
You are saving the CORRECT ID's to the DB...but when you load them you are treating the ID as the LISTINDEX! Hahahaha

VB Code:

Private Sub FindItem(ByVal cboName As ComboBox, ByVal strID As String)

Try
cboName.SelectedIndex = CInt(strID) - 1
Catch ex As Exception
MessageBox.Show(ex.Message.ToString)
End Try

End Sub

Wrong wrong wrong

Woof

Ok, then how should I be doing it?

**Wokawidget** · Jun 24th, 2004, 05:55 AM

1stly if your FormShow use:

VB Code:

Call FindItem(cboSupplier, CLng(dr("SupplierID").ToString))
Call FindItem(cboCategory, CLng(dr("CategoryID").ToString))

Then use:

VB Code:

Private Sub FindItem(ByVal cboName As ComboBox, ByVal lngID As Long)
        Try
            Dim lngIndex As Long
            Dim lItem As ListItemNumeric
            For lngIndex = 0 To cboName.Items.Count - 1
                lItem = CType(cboName.Items.Item(lngIndex), ListItemNumeric)
                If lItem.ID = lngID Then
                    cboName.SelectedIndex = lngIndex
                    Exit For
                End If
            Next lngIndex
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try
    End Sub

Works for me? Does it work on your pc?
Woof

**Wokawidget** · Jun 24th, 2004, 06:03 AM

U know more .NET than me, so is the above correct? Not sure if I have written it properly?
Should I use the CLng function or the CType function???

Woof

**Wokawidget** · Jun 24th, 2004, 06:04 AM

Anyways, your problem was nothing to do with .NET
You would get EXACTLY the same thing happening if you did that in VB6. Stop smoking joints...Hahahaha

Woof

**mendhak** · Jun 24th, 2004, 06:34 AM

I don't know how you got that to work. Set your Option Explicit to ON.

corrected code:

VB Code:

Try
            Dim lngIndex As Long
            Dim lItem As ListItemNumeric
            For lngIndex = 0 To cboName.Items.Count - 1
                ' lItem = CType(cboName.Items.Item(lngIndex), ListItemNumeric)
                lItem = CType(cboName.Items(lngIndex), ListItemNumeric)
                If lItem.ID = CInt(strID) Then
                    cboName.SelectedIndex = lngIndex
                    Exit For
                End If
            Next lngIndex
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try

And looks like this was the way I was supposed to do it. Apparently, the moral of the story is: Do NOT do things the lazy way!

**mendhak** · Jun 24th, 2004, 06:35 AM

You're an unwittingly smart badger.

Oh, and I'm not "better at .NET" than you are. I'm a newbie too, still learning.

Want a joint?

**Wokawidget** · Jun 24th, 2004, 06:39 AM

What do you mean?
What's wrong with:

VB Code:

lItem = CType(cboName.Items.Item(lngIndex), ListItemNumeric)

Item is a property of Items...I don't see what the problem is here.
Item is just the default property of Items, thus Items(1) = Items.Item(1)...Woof
If you have Items.Item(1) and you delete the . and then press . then the .NET IDE does NOT take you to the Item property in the drop down auto thingy...VB6 does...stupid .NET

I am sure I have option explicit on...

Am I missing something?

Groiwl

**mendhak** · Jun 24th, 2004, 07:10 AM

Hold on... I'll give it a try.

{5 mins later}

Yes, that is correct. Same difference. I got the problem here:

VB Code:

If lItem.ID = lngID Then

lngID was never declared, so I don't know how it worked for you. I changed it to strID, and modified the line you mentioned out of personal preference.

**Wokawidget** · Jun 24th, 2004, 07:14 AM

Look at the function I posted:

VB Code:

Private Sub FindItem(ByVal cboName As ComboBox, ByVal lngID As Long)

lngID IS declared.
You must have done something wrong...
U had strID in your code.
I changed this to lngID since it is a long and there is no point in passing it as a string only to convert it back to a long.

I would love a joint

Got given some leaf free the other day

WOOOOoooooooooooooooof

**mendhak** · Jun 24th, 2004, 07:32 AM

Originally posted by Wokawidget

Got given some leaf free the other day

WOOOOoooooooooooooooof

You lucky SOB! Here, leaves are so rare, they bleed.

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