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Object-Oriented database design with the DatabaseObjects library

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31 Jan 20076 min read 110.2K   3.9K   64  
Demonstrates creating object-oriented database systems with the DatabaseObjects library.
 
Option Strict Off
Option Explicit On 

Imports NorthwindDatabase
Imports System.Windows.Forms

Friend Class frmSuppliers
    Inherits System.Windows.Forms.Form

#Region "Windows Form Designer generated code "
	Public Sub New()
		MyBase.New()
        'This call is required by the Windows Form Designer.
		InitializeComponent()
	End Sub
	'Form overrides dispose to clean up the component list.
	Protected Overloads Overrides Sub Dispose(ByVal Disposing As Boolean)
		If Disposing Then
			If Not components Is Nothing Then
				components.Dispose()
			End If
		End If
		MyBase.Dispose(Disposing)
	End Sub
	'Required by the Windows Form Designer
	Private components As System.ComponentModel.IContainer
	Public ToolTip1 As System.Windows.Forms.ToolTip
	Public WithEvents cmdDelete As System.Windows.Forms.Button
	Public WithEvents cmdNew As System.Windows.Forms.Button
	Public WithEvents cmdRename As System.Windows.Forms.Button
	Public WithEvents cmdClose As System.Windows.Forms.Button
	Public WithEvents lstSuppliers As System.Windows.Forms.ListBox
	'NOTE: The following procedure is required by the Windows Form Designer
	'It can be modified using the Windows Form Designer.
	'Do not modify it using the code editor.
	<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.components = New System.ComponentModel.Container
        Me.ToolTip1 = New System.Windows.Forms.ToolTip(Me.components)
        Me.cmdDelete = New System.Windows.Forms.Button
        Me.cmdNew = New System.Windows.Forms.Button
        Me.cmdRename = New System.Windows.Forms.Button
        Me.cmdClose = New System.Windows.Forms.Button
        Me.lstSuppliers = New System.Windows.Forms.ListBox
        Me.SuspendLayout()
        '
        'cmdDelete
        '
        Me.cmdDelete.BackColor = System.Drawing.SystemColors.Control
        Me.cmdDelete.Cursor = System.Windows.Forms.Cursors.Default
        Me.cmdDelete.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.cmdDelete.ForeColor = System.Drawing.SystemColors.ControlText
        Me.cmdDelete.Location = New System.Drawing.Point(188, 404)
        Me.cmdDelete.Name = "cmdDelete"
        Me.cmdDelete.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.cmdDelete.Size = New System.Drawing.Size(81, 24)
        Me.cmdDelete.TabIndex = 3
        Me.cmdDelete.Text = "Delete"
        '
        'cmdNew
        '
        Me.cmdNew.BackColor = System.Drawing.SystemColors.Control
        Me.cmdNew.Cursor = System.Windows.Forms.Cursors.Default
        Me.cmdNew.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.cmdNew.ForeColor = System.Drawing.SystemColors.ControlText
        Me.cmdNew.Location = New System.Drawing.Point(12, 404)
        Me.cmdNew.Name = "cmdNew"
        Me.cmdNew.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.cmdNew.Size = New System.Drawing.Size(81, 24)
        Me.cmdNew.TabIndex = 1
        Me.cmdNew.Text = "&New"
        '
        'cmdRename
        '
        Me.cmdRename.BackColor = System.Drawing.SystemColors.Control
        Me.cmdRename.Cursor = System.Windows.Forms.Cursors.Default
        Me.cmdRename.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.cmdRename.ForeColor = System.Drawing.SystemColors.ControlText
        Me.cmdRename.Location = New System.Drawing.Point(100, 404)
        Me.cmdRename.Name = "cmdRename"
        Me.cmdRename.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.cmdRename.Size = New System.Drawing.Size(81, 24)
        Me.cmdRename.TabIndex = 2
        Me.cmdRename.Text = "&Rename"
        '
        'cmdClose
        '
        Me.cmdClose.BackColor = System.Drawing.SystemColors.Control
        Me.cmdClose.Cursor = System.Windows.Forms.Cursors.Default
        Me.cmdClose.DialogResult = System.Windows.Forms.DialogResult.Cancel
        Me.cmdClose.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.cmdClose.ForeColor = System.Drawing.SystemColors.ControlText
        Me.cmdClose.Location = New System.Drawing.Point(328, 404)
        Me.cmdClose.Name = "cmdClose"
        Me.cmdClose.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.cmdClose.Size = New System.Drawing.Size(81, 24)
        Me.cmdClose.TabIndex = 4
        Me.cmdClose.Text = "&Close"
        '
        'lstSuppliers
        '
        Me.lstSuppliers.BackColor = System.Drawing.SystemColors.Window
        Me.lstSuppliers.Cursor = System.Windows.Forms.Cursors.Default
        Me.lstSuppliers.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.lstSuppliers.ForeColor = System.Drawing.SystemColors.WindowText
        Me.lstSuppliers.ItemHeight = 14
        Me.lstSuppliers.Location = New System.Drawing.Point(12, 12)
        Me.lstSuppliers.Name = "lstSuppliers"
        Me.lstSuppliers.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.lstSuppliers.Size = New System.Drawing.Size(397, 382)
        Me.lstSuppliers.TabIndex = 0
        '
        'frmSuppliers
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.BackColor = System.Drawing.SystemColors.Control
        Me.CancelButton = Me.cmdClose
        Me.ClientSize = New System.Drawing.Size(420, 435)
        Me.Controls.Add(Me.cmdDelete)
        Me.Controls.Add(Me.cmdNew)
        Me.Controls.Add(Me.cmdRename)
        Me.Controls.Add(Me.cmdClose)
        Me.Controls.Add(Me.lstSuppliers)
        Me.Cursor = System.Windows.Forms.Cursors.Default
        Me.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.Location = New System.Drawing.Point(3, 29)
        Me.MaximizeBox = False
        Me.MinimizeBox = False
        Me.Name = "frmSuppliers"
        Me.RightToLeft = System.Windows.Forms.RightToLeft.No
        Me.ShowInTaskbar = False
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterParent
        Me.Text = "Suppliers"
        Me.ResumeLayout(False)

    End Sub
#End Region 

	Private Sub LoadSuppliers()
		
        Dim objSupplier As Supplier
		
		With Me.lstSuppliers
			.Items.Clear()
			
            'To use the For Each enumerator see the GetEnumerator function in the Suppliers class
            For Each objSupplier In NorthwindDB.Suppliers
                .Items.Add(objSupplier.Name)
            Next

            ''Alternatively you can interate using the ObjectByOrdinal
            'Dim intIndex As Integer
            'For intIndex = 0 To NorthwindDB.Suppliers.Count - 1
            '    .Items.Add(NorthwindDB.Suppliers(intIndex).Name)
            'Next

        End With
		
	End Sub
	
	Private Sub cmdNew_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdNew.Click
		
        Dim objSupplier As Supplier
		Dim strNewSupplierName As String
		
        strNewSupplierName = InputDialog.InputBox("Please enter the name of the new supplier:", "", "")
		
        If strNewSupplierName <> Nothing Then
            If NorthwindDB.Suppliers.Exists(strNewSupplierName) Then
                MessageBox.Show("Supplier '" & strNewSupplierName & "' already exists.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
            Else
                objSupplier = New Supplier
                objSupplier.Name = strNewSupplierName
                objSupplier.Save()
                LoadSuppliers()
            End If
        End If
		
	End Sub
	
	Private Sub cmdRename_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdRename.Click
		
		Dim strNewSupplierName As String
        Dim objSupplier As Supplier
		
		If Me.lstSuppliers.SelectedIndex >= 0 Then
            objSupplier = NorthwindDB.Suppliers(Me.lstSuppliers.Text)
            strNewSupplierName = InputDialog.InputBox("Please enter the new supplier name for '" & objSupplier.Name & "'.", "", objSupplier.Name).Trim
            If strNewSupplierName <> Nothing Then
                'if the new name is the same as the old name then do nothing
                If String.Compare(strNewSupplierName, objSupplier.Name, ignorecase:=True) = 0 Then

                ElseIf NorthwindDB.Suppliers.Exists(strNewSupplierName) Then
                    MessageBox.Show("This supplier name already exists.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
                Else
                    objSupplier.Name = strNewSupplierName
                    objSupplier.Save()
                    LoadSuppliers()
                End If
            End If
        Else
            MessageBox.Show("Please select a supplier to rename.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
		End If
		
	End Sub
	
	Private Sub cmdDelete_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdDelete.Click
		
        Dim objSupplier As Supplier
		
		If Me.lstSuppliers.SelectedIndex >= 0 Then
            objSupplier = NorthwindDB.Suppliers(Me.lstSuppliers.Text)
			If objSupplier.IsDeletable Then
                If MessageBox.Show("Are you sure you want to delete supplier '" & objSupplier.Name & "'.", "", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = DialogResult.Yes Then
                    NorthwindDB.Suppliers.Delete(objSupplier)
                    LoadSuppliers()
                End If
            Else
                MessageBox.Show("Supplier '" & objSupplier.Name & "' cannot be deleted, because it is a supplier of an existing product.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
			End If
		Else
            MessageBox.Show("Please select a supplier to delete.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
		End If
		
	End Sub
	
	Private Sub frmSuppliers_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
		
		LoadSuppliers()
		
	End Sub
	
	Private Sub cmdClose_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdClose.Click
		
		Me.Close()
		
	End Sub
End Class

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Written By
Toby Wicks
United States United States
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

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Posted 30 Nov 2005

Article Copyright 2005 by Toby Wicks
Everything else Copyright © CodeProject, 1999-2024

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