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Visual Basic(Microsoft): Version 5 & 6 FAQ
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Processing User Input
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Transferring data from one form to another
Posted: 8 Jan 01
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There's 4 main ways to transfer data from one form to another:
1) Use global variables. They're ugly, but they get the job done. Just make sure that you're not using them for another purpose in other parts of your code, or you'll have a debugging nightmare on your hands! Not Recommended.
2) Use public variables or public properties on the called form. This is a very handy way to transfer data. It also abstracts some of the data passing, and allows the VB parameter pop-up window to remind you of what you called things. You can also make read-only and write-only parameters by using the appropiate Property statements. Highly Recommended.
3) Use a public sub/function in the called form to accept your variables. Good for modal dialog-style forms, where you can show the form, let the user do something with the contents, then send the results back (use ByRef function parameters). Can be a little tricky to handle the form show/unload coding for the novice. Recommended.
4) Write the variables to a database table. It's slow, complicated, and Not Recommended.
You can also do variations on #'s 2 and 3, where the called form calls back into the calling form to get it's data. It's tricky, because you first have to pass a reference to the calling form to the called form so the called form knows who to ask for it's data. There might be a special situation where this needs to be used, but I can't think of one off-hand.
Here's an example of technique number 2.
Cut and paste this into a text document and save it as "form1.frm"
VERSION 5.00
Begin VB.Form Form1
Caption = "Form1"
ClientHeight = 1695
ClientLeft = 60
ClientTop = 345
ClientWidth = 4350
LinkTopic = "Form1"
ScaleHeight = 1695
ScaleWidth = 4350
StartUpPosition = 3 'Windows Default
Begin VB.CommandButton cmdShowForm2
Caption = "Show Form2"
Height = 375
Left = 2400
TabIndex = 2
Top = 420
Width = 1575
End
Begin VB.TextBox Text2
Height = 285
Left = 360
TabIndex = 1
Text = "Text2"
Top = 1020
Width = 1335
End
Begin VB.TextBox Text1
Height = 285
Left = 360
TabIndex = 0
Text = "Text1"
Top = 420
Width = 1335
End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Private Sub cmdShowForm2_Click()
Dim MyForm As Form
Set MyForm = New Form2
MyForm.FirstName = Text1.Text
MyForm.LastName = Text2.Text
MyForm.Show vbModal
If Not MyForm.WasCanceled Then
Text1.Text = MyForm.FirstName
Text2.Text = MyForm.LastName
End If
Set MyForm = Nothing
End Sub
Cut and paste this into a text document and save it as "form2.frm"
VERSION 5.00
Begin VB.Form Form2
BackColor = &H00808000&
Caption = "Form2"
ClientHeight = 1815
ClientLeft = 60
ClientTop = 345
ClientWidth = 5745
LinkTopic = "Form2"
ScaleHeight = 1815
ScaleWidth = 5745
StartUpPosition = 3 'Windows Default
Begin VB.CommandButton cmdCancel
Cancel = -1 'True
Caption = "Cancel"
Height = 375
Left = 4260
TabIndex = 3
Top = 900
Width = 1155
End
Begin VB.CommandButton cmdOK
Caption = "OK"
Default = -1 'True
Height = 375
Left = 4260
TabIndex = 2
Top = 300
Width = 1155
End
Begin VB.TextBox Text2
Height = 285
Left = 1680
TabIndex = 1
Top = 960
Width = 1335
End
Begin VB.TextBox Text1
Height = 285
Left = 1680
TabIndex = 0
Top = 360
Width = 1335
End
Begin VB.Label Label1
Alignment = 1 'Right Justify
BackStyle = 0 'Transparent
Caption = "Last: "
Height = 255
Index = 1
Left = 540
TabIndex = 5
Top = 1020
Width = 1035
End
Begin VB.Label Label1
Alignment = 1 'Right Justify
BackStyle = 0 'Transparent
Caption = "First: "
Height = 255
Index = 0
Left = 540
TabIndex = 4
Top = 360
Width = 1035
End
End
Attribute VB_Name = "Form2"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Private m_FirstName As String
Private m_LastName As String
Private m_WasCanceled As Boolean
Public Property Get FirstName() As String
FirstName = m_FirstName
End Property
Public Property Let FirstName(RHS As String)
m_FirstName = RHS
End Property
Public Property Get LastName() As String
LastName = m_LastName
End Property
Public Property Let LastName(RHS As String)
m_LastName = RHS
End Property
Public Property Get WasCanceled() As Boolean
WasCanceled = m_WasCanceled
End Property
Private Sub cmdCancel_Click()
m_WasCanceled = True
Unload Me
End Sub
Private Sub cmdOK_Click()
m_FirstName = Text1.Text
m_LastName = Text2.Text
Unload Me
End Sub
Private Sub Form_Activate()
Static bNotFirstTime As Boolean
If bNotFirstTime Then
' Do nothing
Else
' Is first time here. Load form up
Text1.Text = m_FirstName
Text2.Text = m_LastName
bNotFirstTime = True
End If
End Sub
Private Sub Form_Load()
m_WasCanceled = False
End Sub
To test this, add these two form files to a new, empty .exe project (remove the Form1.frm that VB provides for you first). Enter a name into form1, click the button, and edit the name in form2. When you click OK, the fields in form1 are updated. If you cancel out, they are left alone.
Chip H.
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