frmmain.vb

An example to accompany PCW March 2004 Visual Programming Hands On. To use, open the solution in

Public Class frmMain
	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()

		'Add any initialization after the InitializeComponent() call

	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

	'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.
	Friend WithEvents btnLoad As System.Windows.Forms.Button
	Friend WithEvents btnShowDetail As System.Windows.Forms.Button
	Friend WithEvents dgPupils As System.Windows.Forms.DataGrid
	Friend WithEvents btnNew As System.Windows.Forms.Button
	Friend WithEvents btnDelete As System.Windows.Forms.Button
	<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
		Me.btnLoad = New System.Windows.Forms.Button
		Me.btnShowDetail = New System.Windows.Forms.Button
		Me.dgPupils = New System.Windows.Forms.DataGrid
		Me.btnNew = New System.Windows.Forms.Button
		Me.btnDelete = New System.Windows.Forms.Button
		CType(Me.dgPupils, System.ComponentModel.ISupportInitialize).BeginInit()
		Me.SuspendLayout()
		'
		'btnLoad
		'
		Me.btnLoad.Location = New System.Drawing.Point(296, 16)
		Me.btnLoad.Name = "btnLoad"
		Me.btnLoad.Size = New System.Drawing.Size(96, 32)
		Me.btnLoad.TabIndex = 1
		Me.btnLoad.Text = "Load"
		'
		'btnShowDetail
		'
		Me.btnShowDetail.Location = New System.Drawing.Point(296, 60)
		Me.btnShowDetail.Name = "btnShowDetail"
		Me.btnShowDetail.Size = New System.Drawing.Size(96, 32)
		Me.btnShowDetail.TabIndex = 2
		Me.btnShowDetail.Text = "Show Detail"
		'
		'dgPupils
		'
		Me.dgPupils.DataMember = ""
		Me.dgPupils.HeaderForeColor = System.Drawing.SystemColors.ControlText
		Me.dgPupils.Location = New System.Drawing.Point(8, 8)
		Me.dgPupils.Name = "dgPupils"
		Me.dgPupils.Size = New System.Drawing.Size(280, 304)
		Me.dgPupils.TabIndex = 3
		'
		'btnNew
		'
		Me.btnNew.Location = New System.Drawing.Point(296, 104)
		Me.btnNew.Name = "btnNew"
		Me.btnNew.Size = New System.Drawing.Size(96, 32)
		Me.btnNew.TabIndex = 4
		Me.btnNew.Text = "New"
		'
		'btnDelete
		'
		Me.btnDelete.Location = New System.Drawing.Point(296, 148)
		Me.btnDelete.Name = "btnDelete"
		Me.btnDelete.Size = New System.Drawing.Size(96, 32)
		Me.btnDelete.TabIndex = 5
		Me.btnDelete.Text = "Delete"
		'
		'frmMain
		'
		Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
		Me.ClientSize = New System.Drawing.Size(404, 326)
		Me.Controls.Add(Me.btnDelete)
		Me.Controls.Add(Me.btnNew)
		Me.Controls.Add(Me.dgPupils)
		Me.Controls.Add(Me.btnShowDetail)
		Me.Controls.Add(Me.btnLoad)
		Me.Name = "frmMain"
		Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
		Me.Text = "PCW School App"
		CType(Me.dgPupils, System.ComponentModel.ISupportInitialize).EndInit()
		Me.ResumeLayout(False)

	End Sub

#End Region

	Private dsPupils As DataSet

	Friend Sub LoadData()
		dsPupils = SchoolData.SchoolData.DataModule.GetPupils
		Me.dgPupils.DataSource = dsPupils
		Me.dgPupils.DataMember = "pupils"
		Me.dgPupils.ReadOnly = True

		'design the grid
		Dim ts1 As New DataGridTableStyle
		ts1.MappingName = "pupils"

		' Set other properties.
		ts1.AlternatingBackColor = Color.LightGray

		' Add a GridColumnStyle and set its MappingName 
		Dim idcol As New DataGridTextBoxColumn
		idcol.MappingName = "id"
		idcol.HeaderText = "ID"
		idcol.Width = 30
		ts1.GridColumnStyles.Add(idcol)

		' Add a second column style.
		Dim TextCol As New DataGridTextBoxColumn
		TextCol.MappingName = "firstname"
		TextCol.HeaderText = "First Name"
		TextCol.Width = 100
		ts1.GridColumnStyles.Add(TextCol)

		Dim namecol As New DataGridTextBoxColumn
		namecol.MappingName = "LastName"
		namecol.HeaderText = "Last Name"
		namecol.Width = 100
		ts1.GridColumnStyles.Add(namecol)

		'clear any existing style
		dgPupils.TableStyles.Clear()

		' Add the DataGridTableStyle instances to 
		' the GridTableStylesCollection. 
		dgPupils.TableStyles.Add(ts1)

	End Sub

	Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click
		Me.LoadData()
	End Sub

	Private Sub btnShowDetail_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShowDetail.Click

		Dim cm As CurrencyManager

		If IsNothing(dsPupils) Then Exit Sub

		cm = CType(BindingContext(dsPupils, "pupils"), CurrencyManager)

		'get the ID
		Dim id As Integer
		Dim dr As DataRowView = CType(cm.Current, DataRowView)
		id = CType(dr.Item("ID"), Integer)

		'get the selected pupil
		Dim dsPupil As DataSet = SchoolData.SchoolData.DataModule.GetPupil(id)

		'show the form
		Dim frm As New frmPupil
		frm.MainForm = Me		 ' set ref. to this form, enables us to call LoadData easily
		frm.LoadData(dsPupil)
		frm.Show()
	End Sub

	Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
		MyBase.OnLoad(e)
		Dim sPath As String = Application.ExecutablePath
		sPath = System.IO.Path.GetDirectoryName(sPath)

		If sPath.EndsWith("\bin") Then
			sPath = sPath.Substring(0, Len(sPath) - 4)
		End If

		SchoolData.SchoolData.DataModule = New SchoolData.SchoolData(sPath)

	End Sub

	Private Sub btnNew_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNew.Click
		'get the selected pupil
		Dim dsPupil As DataSet = SchoolData.SchoolData.DataModule.GetNewPupil

		'show the form
		Dim frm As New frmPupil
		frm.MainForm = Me		 ' set ref. to this form, enables us to call LoadData easily
		frm.LoadData(dsPupil)
		frm.Show()
	End Sub

	Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
		Dim cm As CurrencyManager

		If IsNothing(dsPupils) Then Exit Sub

		cm = CType(BindingContext(dsPupils, "pupils"), CurrencyManager)

		'get the current row
		Dim dr As DataRow = CType(cm.Current, DataRowView).Row

		'prompt to save changes
		If MsgBox("OK to delete pupil: " + GetNameFromDataRow(dr) + "?", MsgBoxStyle.OKCancel, "Hands On Programming") = MsgBoxResult.OK Then
			'delete it from the dataset
			dr.Delete()

			'get just the changed data
			Dim dsChanged As DataSet = dsPupils.GetChanges
			SchoolData.SchoolData.DataModule.SavePupils(dsPupils)
		Else
			'reset the dataset 
			dsPupils.RejectChanges()
		End If

	End Sub

	Private Function GetNameFromDataRow(ByVal dr As DataRow) As String
		'purpose: Get name of pupil from datarow, allowing for nulls

		Dim result As String
		If Not dr.IsNull("firstname") Then
			result = CType(dr.Item("firstname"), String) + " "
		End If

		If Not dr.IsNull("lastname") Then
			result += CType(dr.Item("lastname"), String)
		End If

		Return result

	End Function
End Class