vb.net not to accept comma, single quote and double quote

Question

Hi !

I need to filter my all my textbox in my program to accept

all characters except for  comma, single quote, and double quote. (, ' ").

I use the keypress event for this filter. Here is my initial code but is not working.

If (e.KeyChar = Keys.OemQuotes) Then
        e.handled = false
    Else

   End If

In this, if they key entered is a quote then it will not allow.

Something like this and also to include keys.oemcomma.

I need to filter this to prevent error in my database query since comma and quotes are sensitive to it.

Any help is much appreciated!

Thanks,

Pem

Answer 1

Hello,

The following component works similar to a ToolTip, it implements IExtenderProvider Interface and works with TextBox controls only (see function CanExtend logic).

Build your project, open a form, in the toolbox you will see the component at the top of the toolbox. Double click it once which will place one instance in the window below the form. Select any TextBox, at the bottom of the property window there is a category "Type Validator" with a property "SpecialCharacters" which is pre-filled with your two characters. Build/run the project, each TextBox on the form will not allow these two characters. If one or more should allow these characters simple select the TextBox and remove the two characters.

Note there is other functionality which you need not be concerned with but feel free to explore.

Place into a new file named KeyPressValidator.vb

Option Explicit On
Option Strict On
Option Compare Text
Imports System.ComponentModel
Imports System.Windows.Forms
#Region "Enums"
Public Enum CharsAllowSpecialChars
    [None] = 0
    [InList] = 1
    [NotInList] = 2
End Enum
#End Region
<Drawing.ToolboxBitmap(GetType(System.Windows.Forms.TextBox)), _
System.ComponentModel.DesignerCategoryAttribute("Code"), _
ProvideProperty("AllowAlpha", GetType(Control)), _
ProvideProperty("AllowNumeric", GetType(Control)), _
ProvideProperty("AllowSpecialChars", GetType(Control)), _
ProvideProperty("SpecialCharacters", GetType(Control))> _
Public Class KeyPressValidator
    Inherits System.ComponentModel.Component
    Implements IExtenderProvider
    'This hash table stores all the controls extended by this extender provider
    Friend htProvidedProperties As New Hashtable
#Region "IExtenderProvider"
    ''' <summary>
    ''' The Property should be Extend / Not for the TextBox classes
    ''' </summary>
    ''' <param name="extendee"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Function CanExtend(ByVal extendee As Object) As Boolean Implements System.ComponentModel.IExtenderProvider.CanExtend
      If (TypeOf extendee Is TextBox) OrElse (TypeOf extendee Is MaskedTextBox) Then
         Return True
      Else
         Return False
      End If
    End Function
#End Region
#Region "Extensible Properties"
    Private Class KeyValidatorProperties
        Public AllowAlpha As Boolean = True
        Public AllowNumeric As Boolean = True
        Public AllowSpecialChars As CharsAllowSpecialChars = CharsAllowSpecialChars.NotInList
        ' KSG normally this would be set in the IDE property window for each TextBox but
        ' here I default the array to have two characters for a post
        ' http://social.msdn.microsoft.com/Forums/vstudio/en-US/fe3c2ac8-ca67-4393-9d60-4d202bd83b55/vbnet-not-to-accept-comma-single-quote-and-double-quote
        Public SpecialCharacters() As Char = ",'".ToCharArray
    End Class
    <Category("Type Validator")> _
    Sub SetAllowAlpha(ByVal ctrl As Control, ByVal value As Boolean)
        GetControlFromHashtable(ctrl).AllowAlpha = value
    End Sub
    <Category("Type Validator")> _
    Function GetAllowAlpha(ByVal ctrl As Control) As Boolean
        Return GetControlFromHashtable(ctrl).AllowAlpha
    End Function
    <Category("Type Validator")> _
    Sub SetAllowNumeric(ByVal ctrl As Control, ByVal value As Boolean)
        GetControlFromHashtable(ctrl).AllowNumeric = value
    End Sub
    <Category("Type Validator")> _
    Function GetAllowNumeric(ByVal ctrl As Control) As Boolean
        Return GetControlFromHashtable(ctrl).AllowNumeric
    End Function
    <Category("Type Validator")> _
    Sub SetAllowSpecialChars(ByVal ctrl As Control, ByVal value As CharsAllowSpecialChars)
        GetControlFromHashtable(ctrl).AllowSpecialChars = value
    End Sub
    <Category("Type Validator")> _
    Function GetAllowSpecialChars(ByVal ctrl As Control) As CharsAllowSpecialChars
        Return GetControlFromHashtable(ctrl).AllowSpecialChars
    End Function
    <Category("Type Validator")> _
    Sub SetSpecialCharacters(ByVal ctrl As Control, ByVal value As String)
        GetControlFromHashtable(ctrl).SpecialCharacters = value.ToCharArray
    End Sub
    <Category("Type Validator")> _
    Function GetSpecialCharacters(ByVal ctrl As Control) As String
        Return CType(GetControlFromHashtable(ctrl).SpecialCharacters, String)
    End Function
#End Region
#Region "Behavior"
    Private Function GetControlFromHashtable(ByVal ctrl As Control) As KeyValidatorProperties
        If htProvidedProperties.Contains(ctrl) Then
            Return DirectCast(htProvidedProperties(ctrl), KeyValidatorProperties)
        Else
            Dim ProvidedProperties As New KeyValidatorProperties
            'Add A KeyPress Event Handler as the control is added to hash table
            AddHandler ctrl.KeyPress, AddressOf KeyPressHandler
            AddHandler ctrl.TextChanged, AddressOf TextChangedHandler
            htProvidedProperties.Add(ctrl, ProvidedProperties)
            Return ProvidedProperties
        End If
    End Function
   '+++KSG  10/8/2008 1:53:04 PM changed from TextBox to TextBoxBase
   Private Function CleanText(ByVal txtSender As TextBoxBase, ByVal origText As String) As String
      Dim bAlpha As Boolean = GetControlFromHashtable(txtSender).AllowAlpha
      Dim bDigit As Boolean = GetControlFromHashtable(txtSender).AllowNumeric
      Dim bChars As CharsAllowSpecialChars = GetControlFromHashtable(txtSender).AllowSpecialChars
      Dim SpecialCharacters() As Char = GetControlFromHashtable(txtSender).SpecialCharacters
      Dim index As Integer
      Dim sRet As String = ""
      While index < origText.Length
         Dim bCancel As Boolean = True
         Dim character As Char = origText(index)
         If Char.IsControl(character) Then
            bCancel = False
         ElseIf Char.IsLetter(character) AndAlso bAlpha = False Then
            bCancel = True
         ElseIf Char.IsDigit(character) AndAlso bDigit = False Then
            bCancel = True
         ElseIf bChars = CharsAllowSpecialChars.None AndAlso Char.IsLetter(character) = False AndAlso Char.IsDigit(character) = False Then
            bCancel = True
         ElseIf bChars = CharsAllowSpecialChars.NotInList AndAlso Array.IndexOf(SpecialCharacters, character) >= 0 AndAlso Char.IsLetter(character) = False AndAlso Char.IsDigit(character) = False Then
            bCancel = True
         ElseIf bChars = CharsAllowSpecialChars.InList AndAlso Array.IndexOf(SpecialCharacters, character) < 0 AndAlso Char.IsLetter(character) = False AndAlso Char.IsDigit(character) = False Then
            bCancel = True
         Else
            bCancel = False
         End If
         If bCancel = False Then
            sRet &= character
         End If
         index += 1
      End While
      Return sRet
   End Function
    Private Sub TextChangedHandler(ByVal sender As System.Object, ByVal e As System.EventArgs)
      '+++KSG  10/8/2008 1:52:43 PM changed from TextBox to TextBoxBase
      Dim txtSender As TextBoxBase = CType(sender, TextBoxBase)
        Dim sChangedString As String = txtSender.Text
        Dim sCleanString As String = CleanText(txtSender, sChangedString)
        If sChangedString <> sCleanString Then
            txtSender.Text = sCleanString
        End If
    End Sub
    Private Sub KeyPressHandler(ByVal sender As Object, ByVal e As KeyPressEventArgs)
      '+++KSG  10/8/2008 1:51:56 PM changed from TextBox to TextBoxBase
      Dim txtSender As TextBoxBase = CType(sender, TextBoxBase)
        If txtSender.ReadOnly = True Then
            If Char.IsControl(e.KeyChar) Then
                e.Handled = False
            Else
                e.Handled = True
            End If
        Else
            If Char.IsControl(e.KeyChar) Then
                e.Handled = False
            ElseIf Char.IsLetter(e.KeyChar) AndAlso GetControlFromHashtable(txtSender).AllowAlpha = False Then
                e.Handled = True
            ElseIf Char.IsDigit(e.KeyChar) AndAlso GetControlFromHashtable(txtSender).AllowNumeric = False Then
                e.Handled = True
            ElseIf GetControlFromHashtable(txtSender).AllowSpecialChars = CharsAllowSpecialChars.None AndAlso Char.IsLetter(e.KeyChar) = False AndAlso Char.IsDigit(e.KeyChar) = False Then
                e.Handled = True
            ElseIf GetControlFromHashtable(txtSender).AllowSpecialChars = CharsAllowSpecialChars.NotInList AndAlso Array.IndexOf(GetControlFromHashtable(txtSender).SpecialCharacters, e.KeyChar) >= 0 AndAlso Char.IsLetter(e.KeyChar) = False AndAlso Char.IsDigit(e.KeyChar) = False Then
                e.Handled = True
            ElseIf GetControlFromHashtable(txtSender).AllowSpecialChars = CharsAllowSpecialChars.InList AndAlso Array.IndexOf(GetControlFromHashtable(txtSender).SpecialCharacters, e.KeyChar) < 0 AndAlso Char.IsLetter(e.KeyChar) = False AndAlso Char.IsDigit(e.KeyChar) = False Then
                e.Handled = True
            Else
                e.Handled = False
            End If
        End If
    End Sub
#End Region
End Class

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Answer 2

Hello,

I have moved this thread to Visual Basic for better response.

Best regards,

---

Amanda Zhu
MSDN Community Support | Feedback to us
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