Need help with this custom control

hi all,

i created a custom control that accepts only datetime values.

http://www.vbforums.com/showthread.php?p=3551859

but i'm having some issues with it when it is bound to a column and then i navigate thru records. it seems to trigger a rowchange to all navigated records even though i haven't manually change anything on these records.

this is affecting the last_update_date and last_updated_by fields of my tables. i need to only affect records that were manually changed.

can anyone help me?

also, any date field should be bound to the Value property of this control instead of Text. haven't figured out how to remove the Text from bindable properties yet.

thanks

hi,

no one?

i've pasted my code below in case nobody wants to check out the source.

Code:

---

Public Class DateTimeItem
  Inherits System.Windows.Forms.TextBox

  Dim _Value As Nullable(Of DateTime) = Nothing
  Dim _FormatMask As String = "MM/dd/yyyy" 'Default
  Dim _Required As Boolean = False 'Default
  Dim _RequiredBackColor As Color = Color.LightYellow 'Default
  Dim _Text As String = String.Empty

  Public Property FormatMask() As String
    Get
      Return _FormatMask
    End Get
    Set(ByVal value As String)
      If value <> String.Empty Then
        _FormatMask = value
      End If
    End Set
  End Property

  <Bindable(True)> _
  Public Property Value() As Nullable(Of DateTime)
    Get
      Return _Value
    End Get
    Set(ByVal value As Nullable(Of DateTime))
      If value.HasValue Then
        Me.Text = UCase(value.Value.ToString(_FormatMask))
        _Value = value
      Else
        Me.Text = String.Empty
      End If
    End Set
  End Property

  Public Property Required() As Boolean
    Get
      Return _Required
    End Get
    Set(ByVal value As Boolean)
      _Required = value

      If _Required = True Then
        MyBase.BackColor = _RequiredBackColor
      Else
        MyBase.BackColor = SystemColors.Window
      End If
    End Set
  End Property

  Public Property RequiredBackColor() As Color
    Get
      Return _RequiredBackColor
    End Get
    Set(ByVal value As Color)
      If _Required = True Then
        MyBase.BackColor = _RequiredBackColor
      Else
        MyBase.BackColor = SystemColors.Window
      End If
    End Set
  End Property

  Public Sub ShowCalendar()
    Dim fcalendar As New CalendarForm
    With fcalendar
      .Source = Me
      .ShowDialog()
    End With
  End Sub

  Private Sub DateTimeItem_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.DoubleClick
    Try
      ShowCalendar()
    Catch ex As Exception
      Me.Focus()
      Me.SelectAll()
      Beep()
    End Try
  End Sub

  Private Sub DateTimeItem_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles Me.Validating
    Try
      MsgBox(MyBase.Text.Length.ToString)
      If MyBase.Text.Length > 0 Then
        If Me.Value.HasValue Then
          If DateTime.ParseExact(Me.Text, _FormatMask, CultureInfo.InvariantCulture) <> DateTime.ParseExact(Me.Value.Value.ToString(_FormatMask), _FormatMask, CultureInfo.InvariantCulture) Then
            Me.Value = DateTime.ParseExact(Me.Text, _FormatMask, CultureInfo.InvariantCulture)
          End If
        End If
      End If
    Catch ex As Exception
      Me.Focus()
      Me.SelectAll()
    End Try
  End Sub
End Class

---

thanks

First up, you should be overriding the OnValidating method, not handling the Validating event.

As for the issue, try checking in your Value setter whether the actual value has changed and only set the Text property if it has.

hi,

thanks for the tip.

i've changed my validating process into

Code:

---

  Protected Overrides Sub OnValidating(ByVal e As System.ComponentModel.CancelEventArgs)
    MyBase.OnValidating(e)
    Try
      MsgBox(MyBase.Text.Length.ToString)
      If MyBase.Text.Length > 0 Then
        If Me.Value.HasValue Then
          If DateTime.ParseExact(Me.Text, _FormatMask, CultureInfo.InvariantCulture) <> DateTime.ParseExact(Me.Value.Value.ToString(_FormatMask), _FormatMask, CultureInfo.InvariantCulture) Then
            Me.Value = DateTime.ParseExact(Me.Text, _FormatMask, CultureInfo.InvariantCulture)
          End If
        End If
      End If
    Catch ex As Exception
      Me.Focus()
      Me.SelectAll()
    End Try
  End Sub

---

also, i'm having a bit of a problem getting the logic for checking if the value has changed. i have this set of codes but doesn't seem to work still.

Code:

---

  <Bindable(True)> _
  Public Property Value() As Nullable(Of DateTime)
    Get
      Return _Value
    End Get
    Set(ByVal value As Nullable(Of DateTime))
      If value.HasValue And _Value.HasValue Then
        If _Value.Value <> value.Value Then
          _Value = value
          Me.Text = UCase(value.Value.ToString(_FormatMask))
        End If
      ElseIf value.HasValue And _Value.HasValue = False Then
        _Value = value
        Me.Text = UCase(value.Value.ToString(_FormatMask))
      ElseIf value.HasValue = False And _Value.HasValue = True Then
        _Value = value
        Me.Text = UCase(value.Value.ToString(_FormatMask))
      Else
        Me.Text = String.Empty
      End If
    End Set
  End Property

---

can you help me figure out what's wrong?

thanks

You use the Equals method to compare Nullable types. Try this code for an example of its behaviour:

Code:

---

Dim d1 As Nullable(Of DateTime) = Nothing
Dim d2 As Nullable(Of DateTime) = Nothing
Dim d3 As Nullable(Of DateTime) = #1/1/2001#
Dim d4 As Nullable(Of DateTime) = #1/1/2001#
Dim d5 As Nullable(Of DateTime) = #2/2/2002#

If d1.Equals(d2) Then
    MessageBox.Show("Nothing equals Nothing")
Else
    MessageBox.Show("Nothing does not equal Nothing")
End If

If d1.Equals(d3) Then
    MessageBox.Show("Nothing equals #1/1/2001#")
Else
    MessageBox.Show("Nothing does not equal #1/1/2001#")
End If

If d3.Equals(d1) Then
    MessageBox.Show("#1/1/2001# equals Nothing")
Else
    MessageBox.Show("#1/1/2001# does not equal Nothing")
End If

If d3.Equals(d4) Then
    MessageBox.Show("#1/1/2001# equals #1/1/2001#")
Else
    MessageBox.Show("#1/1/2001# does not equal #1/1/2001#")
End If

If d3.Equals(d5) Then
    MessageBox.Show("#1/1/2001# equals #2/2/2002#")
Else
    MessageBox.Show("#1/1/2001# does not equal #2/2/2002#")
End If

---

Your code should be:

vb.net Code:

Set(ByVal value As Nullable(Of DateTime))
    If Not _Value.Equals(value) Then
        _Value = value
 
        If value.HasValue Then
            Me.Text = value.Value.ToString(_FormatMask).ToUpper()
        Else
            Me.Text = String.Empty
        End If
    End If
End Set

hi,

thanks for the suggestion.

i changed my code copying yours like so

Code:

---

  <Bindable(True)> _
  Public Property Value() As Nullable(Of DateTime)
    Get
      Return _Value
    End Get
    Set(ByVal value As Nullable(Of DateTime))
      If Not _Value.Equals(value) Then
        _Value = value

        If value.HasValue Then
          Me.Text = value.Value.ToString(_FormatMask).ToUpper()
        Else
          Me.Text = String.Empty
        End If
      End If
    End Set
  End Property

---

but the records navigated still updates even if there were no changes on them. i placed a breakpoint on this block and when i tried to save a record, it loops around 4 times. the first 3 times it does not go inside the If value.HasValue block but the 4th time it goes there.

not sure what's causing it to go there though. do you have any thoughts on this?

thanks

hi,

i tried to do some more tests.

i added a code in my form to catch the rowstate value of the previous row whenever the position changes.

it then kept on saying "Modified" each time i tried to navigate to other records.

i then removed the custom control from my form and then tried to navigate to other records.

this time it kept saying "Unchanged".

i guess there might be something wrong with the custom control.

i noticed one other thing.

if the property that is bound to a datatable column is not a property of the MyBase object, it seems to change the rowstate to Modified even though there are no codes inside that Property Block.

could this be a bug?