带有相应文本字段的组合框的验证

Posted 2021-02-26

Private Sub cboColor_BeforeUpdate(Cancel As Integer)
 
    ' Validation for combo box with a corresponding text field. 
    ' When users select "Other" in cboColor, they are encouraged to specify in txtOther what they mean. 
    ' If they enter something in txtOther and then decide to change or delete their answer in cboColor, this routine
    ' tells them the data in txtOther will be deleted. This prevents orphaned data being stored in txtOther 
    ' when cboColor is blank or <> "Other".
 
    If Not IsNull(Me.txtOther) Then     				' If txtOther has data
        If Not Me.cboColor.Value = "Other" Or IsNull(Me.cboColor) Then     ' and the user selects something different than "Other", ask the user to confirm the change
            If MsgBox("Changing this answer from 'Other' will delete the information in the adjacent text field. " & _
            Chr(13) & Chr(13) & "Continue?", vbQuestion + vbYesNo + vbDefaultButton2, "Change Answer?") = vbYes Then     
							' If the user clicks 'Yes'
                Me.txtOther = Null     			' delete the data in txtOther
                 Else                                	' Otherwise, if the user doesn't click 'Yes'
                Cancel = True                   	' don't go through with the change (i.e., cancel the update),
                Me.cboColor.Undo                      	' restore the value of cboOther to the original answer (i.e., 'Other')
                Exit Sub                        	' and leave this routine
            End If
        End If
    End If
 
    'Check the final value in cboColor to determine whether to enable or disable txtOther.
    'If cboColor = 'Other', set txtOther's enabled property to True (i.e., -1).
    'If cboColor <> 'Other', set txtOther's enabled property to False (i.e., 0).
 
    Me.txtOther.Enabled = IIf(Me.cboColor = "Other", -1, 0)
 
End Sub