How to create a DropDownList control through data binding

The following code explains you how to create a DropDownList control through data binding.

Code for the Default.aspx:

Imports System.Data

Partial Class _Default

    Inherits System.Web.UI.Page

    Sub Selection_Change(ByVal sender As Object, ByVal e As EventArgs)

        ' Here we set the background color for days in the Calendar control

        ' based on the value selected in the DropDownList control.

        Calendar1.DayStyle.BackColor = _

            System.Drawing.Color.FromName(DropDownColors.SelectedItem.Value)

    End Sub

    Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load

        ' Load data for the DropDownList control only once, when the

        ' page is first loaded.

        If Not IsPostBack Then

            ' These few lines for Specify the data source and field names for the Text

            ' and Value properties of the items in the DropDownList control.

            DropDownColors.DataSource = CreateDataSource()

            DropDownColors.DataTextField = "ColorListTextField"

            DropDownColors.DataValueField = "ColorListValueField"

            ' Bind the data to the control.

            DropDownColors.DataBind()

            ' Set the default selected item, if desired.

            DropDownColors.SelectedIndex = 0

        End If

    End Sub

    Function CreateDataSource() As ICollection

        ' Create a table to store data for the DropDownList control.

        Dim dt As DataTable = New DataTable()

        ' Define the columns of the table.

        dt.Columns.Add(New DataColumn("ColorListTextField", GetType(String)))

        dt.Columns.Add(New DataColumn("ColorListValueField", GetType(String)))

        ' Populate the table with sample values.

        dt.Rows.Add(CreateRow("Black", "Black", dt))

        dt.Rows.Add(CreateRow("Silver", "Silver", dt))

        dt.Rows.Add(CreateRow("White", "White", dt))

        dt.Rows.Add(CreateRow("Blue", "Blue", dt))

        dt.Rows.Add(CreateRow("Yellow", "Yellow", dt))

        ' Create a DataView from the DataTable to act as the data source

        ' for the DropDownList control.

        Dim dv As DataView = New DataView(dt)

        Return dv

    End Function

    Function CreateRow(ByVal Text As String, ByVal Value As String, ByVal dt As DataTable) As DataRow

        ' Create a DataRow using the DataTable defined in the

        ' CreateDataSource method.

        Dim dr As DataRow = dt.NewRow()

        dr(0) = Text

        dr(1) = Value

        Return dr

    End Function

End Class