How to populate a combobox and listbox

[enak]

What is the best way to populate a combobox and a listbox? I need to populate them from a database. I can do it with the following code:

While dr.Read
Me.lstClassifications.Items.Add(dr.GetValue(1))
End While

but I am not sure that I am getting id's along with the display value.

I am using a datareader but when I use the code that I find here I get an unhandled exception.

This is for a window application using VB.NET.

Please help

Thanks,
enak.

 

[ThatRickGuy]

me.lstClassivications.datasource = dr
me.lstClassivications.displayField = "Column Name"
me.lstClassivications.valuefield = "Column Name"

err something like that.

-Rick

VB.Net Forum forum796 forum855 ASP.NET Forum
I believe in killer coding ninja monkeys.

 

[enak]

This does not work for me. I get this error:

An unhandled exception of type 'System.Exception' occurred in system.windows.forms.dll

Additional information: Complex DataBinding accepts as a data source either an IList or an IListSource

Any Ideas how to fix it?

 

[earthandfire]

I've not tested anything but you will probably need to use a dastaset rather than a datareader to take advantage of Rick's suggestion.

Hope this helps.

 

[BobRodes]

If you want to get id's along with the display value, you can do data binding. However, you can also do it "by hand."

The .Net ListBox is much more flexible than its predecessors. While the ItemData is no longer supported, it's superfluous, because the ListBox actually holds an array of objects. So, you can create a class that holds any information that you want, and populate the ListBox's Items collection with instances of it.

Ok. Create a class that identifies a list item, such as ListItem. You'll have to override its default ToString method, since the default implementation of ToString comes from System.Object, and returns the string value of the class from which the object was instantiated (in this case, all of your listbox lines would say something like "System.Object.myListItem", as I learned the hard way).

Class myListItem
   Public myID as Integer
   Public myString as String

   Sub New(ByVal i As Integer, ByVal s As String)
      Me.myId = i
      Me.myString = s
   End Sub

   Overrides Function ToString() As String
      Return myString
   End Function
End Class

Now, to use it in a ListBox:

With ListBox1.Items
   .Add(New myListItem(1, "Peter Piper"))
   .Add(New myListItem(2, "Pickled Peppers"))
   'etc.
End With

To access the myId property above, you'll have to recast the list item to what it was (the Add method converts the object into an Item object--I think--so you have to cast it back to access the properties):

myInteger = DirectCast(ListBox1.Items(1), myListItem).myId

Et voila! This has always worked for me.

HTH

Bob

 

[BobRodes]

By the way, I use a DataReader to get my data with this technique.

 

[earthandfire]

That way you can, Bob, because you are doing everything manually. I was simply commenting on Rick's suggestion.


Hope this helps.

 

[mansii]

Perhaps,

While dr.Read
    Me.lstClassifications.Items.Add(dr(1).ToString)
End While

Make sure that you have the index 1 in dr.

Regards,
mansii