VB.NET - Iterieren durch Steuerelemente in einem Container-Objekt

Question

Ich habe ein Formular mit einer Schaltfläche "Löschen".

Wenn der Benutzer auf "Löschen" klickt, möchte ich den Wert aller sichtbaren Elemente des Formulars löschen. Im Falle von Datumselementen möchte ich sie auf das aktuelle Datum zurücksetzen.

Alle meine Steuerelemente sind in einem Panel enthalten.

Im Moment mache ich das mit dem folgenden Code. Gibt es einen einfacheren Weg als die manuelle Überprüfung für jeden Kontrolltyp? Diese Methode scheint übermäßig unhandlich zu sein.

Um die Sache noch schlimmer zu machen, muss ich das ganze Monster mit einer überladenen "GroupBox"-Version wiederholen, um rekursiv Steuerelemente innerhalb von Sub-Containern zu löschen (z. B. einen Gruppenrahmen innerhalb des Panels).

Edit: Dank Ihrer Vorschläge wurde der folgende Code stark vereinfacht.

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
    'User clicks Clear, so clear all the controls within this panel
    ClearAllControls(panMid, True) 'True indicates that yes, i want to recurse through sub-containers
End Sub

ClearAllControls(ByRef container As Panel, Optional Recurse As Boolean = True)   
  'Clear all of the controls within the container object
  'If "Recurse" is true, then also clear controls within any sub-containers
  Dim ctrl As Control
  For Each ctrl In container.Controls
      If (ctrl.GetType() Is GetType(TextBox)) Then
          Dim txt As TextBox = CType(ctrl, TextBox)
          txt.Text = ""
      End If
      If (ctrl.GetType() Is GetType(CheckBox)) Then
          Dim chkbx As CheckBox = CType(ctrl, CheckBox)
          chkbx.Checked = False
      End If
      If (ctrl.GetType() Is GetType(ComboBox)) Then
          Dim cbobx As ComboBox = CType(ctrl, ComboBox)
          cbobx.SelectedIndex = -1
      End If
      If (ctrl.GetType() Is GetType(DateTimePicker)) Then
          Dim dtp As DateTimePicker = CType(ctrl, DateTimePicker)
          dtp.Value = Now()
      End If

      If Recurse Then
          If (ctrl.GetType() Is GetType(Panel)) Then
              Dim pnl As Panel = CType(ctrl, Panel)
              ClearAllControls(pnl, Recurse)
          End If
          If ctrl.GetType() Is GetType(GroupBox) Then
              Dim grbx As GroupBox = CType(ctrl, GroupBox)
              ClearAllControls(grbx, Recurse)
          End If
      End If
  Next
End Sub

@Theraccoonbear: Ihr Vorschlag gefällt mir, aber wenn ich die Erklärung so ändere:

Private Sub ClearAllControls(ByRef controls As ControlCollection, Optional ByVal Recurse As Boolean = True)

Dann gibt diese Zeile mir "Unable to cast object of type 'ControlCollection' to type 'ControlCollection'.":

  ClearAllControls(panMid.Controls)

Answer 1

Hier funktioniert es für alle inneren Kontrollen.
Fügen Sie hinzu, ob Sie andere Kontrollen löschen müssen.

Private Sub ClearAll()
    Try
        For Each ctrl As Control In Me.Controls
            If ctrl.[GetType]().Name = "Panel" Then
                ClearControls(ctrl)
            End If

            If ctrl.[GetType]().Name = "GroupBox" Then
                ClearControls(ctrl)
            End If
            If ctrl.[GetType]().Name = "ComboBox" Then
                Dim tb As ComboBox = TryCast(ctrl, ComboBox)
                tb.SelectedText = ""
            End If

            If ctrl.[GetType]().Name = "TabControl" Then
                ClearControls(ctrl)
            End If

            If ctrl.[GetType]().Name = "TextBox" Then
                Dim tb As TextBox = TryCast(ctrl, TextBox)
                tb.Clear()
            End If

            If ctrl.[GetType]().Name = "RadioButton" Then
                Dim tb As RadioButton = TryCast(ctrl, RadioButton)
                tb.Checked = False
            End If

            If ctrl.[GetType]().Name = "CheckBox" Then
                Dim tb As CheckBox = TryCast(ctrl, CheckBox)
                tb.Checked = False
            End If

            If ctrl.[GetType]().Name = "ComboBox" Then
                Dim tb As ComboBox = TryCast(ctrl, ComboBox)
                tb.SelectedIndex = 0
            End If

            If ctrl.[GetType]().Name = "RichTextBox" Then
                Dim tb As RichTextBox = TryCast(ctrl, RichTextBox)
                tb.Clear()

            End If
        Next
    Catch ex As Exception
        MessageBox.Show(ex.Message, "Error Message", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End Try
End Sub

Private Sub ClearControls(ByVal Type As Control)

    Try
        For Each ctrl As Control In Type.Controls

            If ctrl.[GetType]().Name = "TextBox" Then
                Dim tb As TextBox = TryCast(ctrl, TextBox)
                tb.Clear()
            End If

            If ctrl.[GetType]().Name = "Panel" Then
                ClearControls(ctrl)
            End If

            If ctrl.[GetType]().Name = "GroupBox" Then
                ClearControls(ctrl)
            End If

            If ctrl.[GetType]().Name = "TabPage" Then
                ClearControls(ctrl)
            End If

            If ctrl.[GetType]().Name = "ComboBox" Then
                Dim tb As ComboBox = TryCast(ctrl, ComboBox)
                tb.SelectedText = ""
            End If

            If ctrl.[GetType]().Name = "RadioButton" Then
                Dim tb As RadioButton = TryCast(ctrl, RadioButton)
                tb.Checked = False
            End If

            If ctrl.[GetType]().Name = "CheckBox" Then
                Dim tb As CheckBox = TryCast(ctrl, CheckBox)
                tb.Checked = False
            End If

            If ctrl.[GetType]().Name = "RichTextBox" Then
                Dim tb As RichTextBox = TryCast(ctrl, RichTextBox)
                tb.Clear()

            End If
        Next
    Catch ex As Exception
        MessageBox.Show(ex.Message, "Error Message", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End Try
End Sub

Answer 2

Dies stammt direkt aus einer Artikel Techniken zu diskutieren, die jetzt verwendet werden können, da Control Arrays beim Übergang von VB6 zu VB.NET abgeschafft wurden.

Private Sub ClearForm(ByVal ctrlParent As Control)
    Dim ctrl As Control
    For Each ctrl In ctrlParent.Controls
        If TypeOf ctrl Is TextBox Then
           ctrl.Text = ""
        End If
        ' If the control has children, 
        ' recursively call this function
        If ctrl.HasChildren Then
            ClearForm(ctrl)
        End If
    Next
End Sub

Answer 3

Public Sub raz(lst As Control.ControlCollection, Optional recursive As Boolean = True)
    For Each ctrl As Control In lst
        If TypeOf ctrl Is TextBox Then
            CType(ctrl, TextBox).Clear()
        End If

        If TypeOf ctrl Is MaskedTextBox Then
            CType(ctrl, MaskedTextBox).Clear()
        End If

        If TypeOf ctrl Is ComboBox Then
            CType(ctrl, ComboBox).SelectedIndex = -1
        End If

        If TypeOf ctrl Is DateTimePicker Then
            Dim dtp As DateTimePicker = CType(ctrl, DateTimePicker)
            dtp.CustomFormat = " "
        End If

        If TypeOf ctrl Is CheckedListBox Then
            Dim clbox As CheckedListBox = CType(ctrl, CheckedListBox)
            For i As Integer = 0 To clbox.Items.Count - 1
                clbox.SetItemChecked(i, False)
            Next
        End If

        If TypeOf ctrl Is RadioButton Then
            CType(ctrl, RadioButton).Checked = False

        End If

        If recursive Then
            If TypeOf ctrl Is GroupBox Then
                raz(CType(ctrl, GroupBox).Controls)
            End If
        End If
    Next
End Sub

Answer 4

Ich präsentiere Ihnen meine ControlIterator Klasse

Quelle: http://pastebin.com/dubt4nPG

Einige Anwendungsbeispiele:

 ControlIterator.Disable(CheckBox1)

 ControlIterator.Enable({CheckBox1, CheckBox2})

 ControlIterator.Check(Of CheckBox)(Me)

 ControlIterator.Uncheck(Of CheckBox)(Me.GroupBox1)

 ControlIterator.Hide(Of CheckBox)("1")

 ControlIterator.PerformAction(Of CheckBox)(Sub(ctrl As CheckBox) ctrl.Visible = True)

 ControlIterator.AsyncPerformAction(RichTextBox1,
                                    Sub(rb As RichTextBox)
                                        For n As Integer = 0 To 9
                                            rb.AppendText(CStr(n))
                                        Next
                                    End Sub)

 ControlIterator.PerformAction(Me.Controls, Sub(c As Control)
                                                c.BackColor = Color.Green
                                            End Sub)

Answer 5

Dies kann bei der zukünftigen Entwicklung helfen ...

GetAllButtons(Me)

Public Sub GetAllButtons(ByRef forms As Object)
    Dim list As New List(Of Button)
    Dim iIndx As Integer
    For Each c In forms.Controls
        For iIndx = 0 To forms.Controls.Count - 1
            If (TypeOf forms.Controls(iIndx) Is Button) Then
                list.Add(forms.Controls(iIndx))
            End If
            If (TypeOf forms.controls(iIndx) Is Panel) Then
                For Each cntrl As Control In forms.controls(iIndx).Controls
                    If TypeOf cntrl Is Button Then
                        list.Add(cntrl)
                    End If
                Next
            End If
        Next
    Next

Button(list.ToArray)

End Sub

Public Sub Button(btn() As Button)
    For Each bt In btn
       Do Something with Buttons
    next
End Sub