defaultvb.aspx.vb

Telerik是很大的第三方软件制造商

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Data.OleDb
Imports System.Drawing
Imports System.Web
Imports System.Web.SessionState
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports Telerik.QuickStart
Imports Telerik.WebControls


Namespace Telerik.CallbackExamplesVB.Functionality.SetFocus
    '/ <summary>
    '/ Summary description for _Default.
    '/ </summary>

    Public Class DefaultVB
        Inherits XhtmlPage


        Protected CallbackTextBox1 As Telerik.WebControls.CallbackTextBox
        Protected Label2 As System.Web.UI.WebControls.Label
        Protected Label3 As System.Web.UI.WebControls.Label
        Protected cbSetFocus As Telerik.WebControls.CallbackCheckBox
        Protected Image1 As System.Web.UI.WebControls.Image
        Protected LoadingPanel1 As Telerik.WebControls.LoadingPanel
        Protected WithEvents ddlContinents As Telerik.WebControls.CallbackDropDownList
        Protected WithEvents ddlCountries As Telerik.WebControls.CallbackDropDownList
        Protected WithEvents ddlCities As Telerik.WebControls.CallbackDropDownList
        Protected lbPath As System.Web.UI.WebControls.Label
        Protected CallbackTextBox2 As Telerik.WebControls.CallbackTextBox


        Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load            
            If Not Page.IsPostBack Then
                LoadContinents()
                ResetControls()
            End If

        End Sub 'Page_Load

        Private Sub LoadContinents()
            Dim path As String = Server.MapPath("~/Callback/Data/Countries.mdb")
            Dim dbCon As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path)
            dbCon.Open()

            Dim adapter As New OleDbDataAdapter("SELECT * FROM Continents", dbCon)
            Dim dt As New DataTable
            adapter.Fill(dt)
            dbCon.Close()

            ddlContinents.DataTextField = "Name"
            ddlContinents.DataValueField = "ID"
            ddlContinents.DataSource = dt
            ddlContinents.DataBind()

            ddlContinents.Items.Insert(0, New ListItem(" - Select a continent - "))

            If ddlContinents.SelectedIndex = -1 Then
                ddlContinents.SelectedIndex = 0
            End If

        End Sub 'LoadContinents


        Private Sub ddlContinents_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlContinents.SelectedIndexChanged
            If ddlContinents.SelectedIndex > 0 Then
                LoadCountries(ddlContinents.SelectedItem.Value)
                LoadCities(ddlCountries.SelectedItem.Value)
                If cbSetFocus.Checked Then
                    ddlContinents.SetFocus(ddlCountries.ClientID)
                End If
            Else
                ddlCountries.Enabled = False
                ddlCities.Enabled = False
                ResetControls()
            End If
            UpdatePath()

        End Sub 'ddlContinents_SelectedIndexChanged


        Private Sub ResetControls()
            If ddlCountries.Items.Count = 0 Then
                ddlCountries.Items.Insert(0, New ListItem("- Select a country - ", "-1"))
            End If
            ddlCountries.SelectedIndex = 0
            If ddlCities.Items.Count = 0 Then
                ddlCities.Items.Insert(0, New ListItem("- Select a city - ", "-1"))
            End If
            ddlCities.SelectedIndex = 0

        End Sub 'ResetControls


        Private Sub UpdatePath()
            lbPath.Text = String.Empty
            If ddlContinents.SelectedIndex > 0 Then
                lbPath.Text += ddlContinents.SelectedItem.Text
                If ddlCountries.SelectedIndex > 0 Then
                    lbPath.Text += " > " + ddlCountries.SelectedItem.Text

                    If ddlCities.SelectedIndex > 0 Then
                        lbPath.Text += " > " + ddlCities.SelectedItem.Text
                    End If
                End If
            End If

        End Sub 'UpdatePath


        Private Sub LoadCountries(ByVal selectedValue As String)
            If selectedValue <> "-1" Then
                Dim path As String = Server.MapPath("~/Callback/Data/Countries.mdb")
                Dim dbCon As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path)
                dbCon.Open()

                Dim adapter As New OleDbDataAdapter("SELECT * FROM Countries WHERE ContinentID = " + selectedValue, dbCon)
                Dim dt As New DataTable
                adapter.Fill(dt)
                dbCon.Close()

                ddlCountries.DataTextField = "Name"
                ddlCountries.DataValueField = "ID"
                ddlCountries.DataSource = dt
                ddlCountries.DataBind()

                ddlCountries.Enabled = True

                ddlCountries.Items.Insert(0, New ListItem("- Select a country -", "-1"))

                If ddlCountries.SelectedIndex = -1 Then
                    ddlCountries.SelectedIndex = 0
                End If
            End If

        End Sub 'LoadCountries


        Private Sub LoadCities(ByVal selectedValue As String)
            If selectedValue <> "-1" Then
                Dim path As String = Server.MapPath("~/Callback/Data/Countries.mdb")
                Dim dbCon As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path)
                dbCon.Open()

                Dim adapter As New OleDbDataAdapter("SELECT * FROM Cities WHERE CountryID = " + selectedValue, dbCon)
                Dim dt As New DataTable
                adapter.Fill(dt)
                dbCon.Close()

                ddlCities.DataTextField = "Name"
                ddlCities.DataValueField = "ID"
                ddlCities.DataSource = dt
                ddlCities.DataBind()

                ddlCities.Items.Insert(0, New ListItem("- Select a city - ", "-1"))

                ddlCities.Enabled = True

                If ddlCities.SelectedIndex = -1 Then
                    ddlCities.SelectedIndex = 0
                End If
            Else
                If ddlCities.Items.Count = 0 Then
                    ddlCities.Items.Insert(0, New ListItem("- Select a city - ", "-1"))
                End If
                ddlCities.SelectedIndex = 0
                ddlCities.Enabled = False
            End If

        End Sub 'LoadCities


        Private Sub ddlCountries_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlCountries.SelectedIndexChanged
            If ddlCountries.SelectedIndex > 0 Then
                LoadCities(ddlCountries.SelectedItem.Value)
                If cbSetFocus.Checked Then
                    ddlContinents.SetFocus(ddlCities.ClientID)
                End If
            End If
            UpdatePath()

        End Sub 'ddlCountries_SelectedIndexChanged


        Private Sub ddlCities_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlCities.SelectedIndexChanged
            UpdatePath()
            If cbSetFocus.Checked Then
                ddlCities.SetFocus(ddlContinents.ClientID)
            End If

        End Sub 'ddlCities_SelectedIndexChanged
    End Class 'DefaultVB
End Namespace 'Telerik.CallbackExamplesVB.Functionality.ClientEvents