Fastest way of filling a combobox from a datatable in VB.Net

Question

The data table in the following code is filled with 7500-+ records. This all loads quickly from the server. The problem is that it takes a while to loop through the data rows to

Answer 1

Try this:

cboColours.DataSource = dtColours 'For Windows Forms or

cboColours.ItemsSource = dtColours 'For WPF

Answer 2

Dim daColours As New SqlDataAdapter("SELECT DISTINCT Rtrim(UPPER(Colour)) As Colour FROM invStockColour WHERE InUse = 1 ORDER BY Colour", dbSQL)

Dim dtColours As New DataTable
daColours.Fill(dtColours)

cboColours.DataSource=dtColours  
cboColours.DisplayMember="Colour"

Answer 3

The fasted way would be to use the AddRange method instead of using Add, something like:

Dim items = dtColours.AsEnumerable().Select(Function(d) DirectCast(d(0).ToString(), Object)).ToArray()
cboColours.Items.AddRange(items)

I did a simple check and using AddRange is ~3x faster than using Add.

Of course allocating an array and filling it with a For loop would probably some milliseconds faster than using Linq.

Answer 4

You could also bind your ComboBox DataSource property to the DataTable. This has the added advantage of binding other column data (such as key values you might not want the user to see).

You should be able to return a DataTable object from your SQLAdapter.

cboColours.DataSource = dtColours
cboColours.DisplayMember = dtColours.Columns("Colour").ToString
cboColours.ValueMember = dtColours.Columns("Colour_id").ToString