TreeList.EditFormShowing Event

Fires when the Edit Form is about to be displayed. Allows you to cancel the action.

Namespace: DevExpress.XtraTreeList

Assembly: DevExpress.XtraTreeList.v24.1.dll

NuGet Packages: DevExpress.Win.Navigation, DevExpress.Win.TreeList

Declaration

C#

[DXCategory("Editor")]
public event EditFormShowingEventHandler EditFormShowing

VB.NET

<DXCategory("Editor")>
Public Event EditFormShowing As EditFormShowingEventHandler

Event Data

The EditFormShowing event's data class is EditFormShowingEventArgs. The following properties provide information specific to this event:

Property	Description
Allow	Gets or sets whether it is allowed to show the Edit Form.
Node	Gets the node for which the Edit Form is about to be shown.

Examples

The control displays a list of booked flights. A user edits flights in the Edit Form. The code below shows how to do the following:

• disable the Return field if the One Way option is selected

  

• set the Return field’s minimum value to the Departure field’s value

  

C#

using DevExpress.XtraEditors;

treeList1.OptionsBehavior.EditingMode = DevExpress.XtraTreeList.TreeListEditingMode.EditForm;
treeList1.EditFormPrepared += TreeList1_EditFormPrepared;
treeList1.EditFormHidden += TreeList1_EditFormHidden;

CheckEdit editOneWay;
DateEdit editDeparture;
DateEdit editReturn;

private void TreeList1_EditFormPrepared(object sender, DevExpress.XtraTreeList.EditFormPreparedEventArgs e) {
    editDeparture = e.BindableControls["Departure"] as DateEdit;
    editReturn = e.BindableControls["Return"] as DateEdit;
    editOneWay = e.BindableControls["One Way"] as CheckEdit;
    if (editOneWay != null)
        editOneWay.EditValueChanging += EditOneWay_EditValueChanging;
    if(editDeparture != null)
        editDeparture.EditValueChanged += EditDeparture_EditValueChanged;
}

private void EditDeparture_EditValueChanged(object sender, EventArgs e) {
    editReturn.Properties.MinValue = (DateTime)editDeparture.EditValue;
}

private void EditOneWay_EditValueChanging(object sender, DevExpress.XtraEditors.Controls.ChangingEventArgs e) {
    if ((bool)e.NewValue)
        editReturn.Enabled = false;
    else
        editReturn.Enabled = true;
}

private void TreeList1_EditFormHidden(object sender, DevExpress.XtraTreeList.EditFormHiddenEventArgs e) {
    if (editOneWay != null)
        editOneWay.EditValueChanging -= EditOneWay_EditValueChanging;
    if(editDeparture != null)
        editDeparture.EditValueChanged -= EditDeparture_EditValueChanged;
    editOneWay = null;
    editDeparture = null;
    editReturn = null;
}

VB.NET

Imports DevExpress.XtraEditors


treeList1.OptionsBehavior.EditingMode = DevExpress.XtraTreeList.TreeListEditingMode.EditForm
AddHandler treeList1.EditFormPrepared, AddressOf TreeList1_EditFormPrepared
AddHandler treeList1.EditFormHidden, AddressOf TreeList1_EditFormHidden

Private editOneWay As CheckEdit
Private editDeparture As DateEdit
Private editReturn As DateEdit

Private Sub TreeList1_EditFormPrepared(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.EditFormPreparedEventArgs)
    editDeparture = TryCast(e.BindableControls("Departure"), DateEdit)
    editReturn = TryCast(e.BindableControls("Return"), DateEdit)
    editOneWay = TryCast(e.BindableControls("One Way"), CheckEdit)
    If editOneWay IsNot Nothing Then
        AddHandler editOneWay.EditValueChanging, AddressOf EditOneWay_EditValueChanging
    End If
    If editDeparture IsNot Nothing Then
        AddHandler editDeparture.EditValueChanged, AddressOf EditDeparture_EditValueChanged
    End If
End Sub

Private Sub EditDeparture_EditValueChanged(ByVal sender As Object, ByVal e As EventArgs)
    editReturn.Properties.MinValue = DirectCast(editDeparture.EditValue, DateTime)
End Sub

Private Sub EditOneWay_EditValueChanging(ByVal sender As Object, ByVal e As DevExpress.XtraEditors.Controls.ChangingEventArgs)
    If DirectCast(e.NewValue, Boolean) Then
        editReturn.Enabled = False
    Else
        editReturn.Enabled = True
    End If
End Sub

Private Sub TreeList1_EditFormHidden(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.EditFormHiddenEventArgs)
    If editOneWay IsNot Nothing Then
        RemoveHandler editOneWay.EditValueChanging, AddressOf EditOneWay_EditValueChanging
    End If
    If editDeparture IsNot Nothing Then
        RemoveHandler editDeparture.EditValueChanged, AddressOf EditDeparture_EditValueChanged
    End If
    editOneWay = Nothing
    editDeparture = Nothing
    editReturn = Nothing
End Sub

The code below shows how to prevent the Edit Form from being shown in a particular case, focus an editor in the Edit Form, subscribe to the editor’s events, and get the clicked button when the Edit Form is closed.

C#

using DevExpress.XtraEditors;
using DevExpress.XtraEditors.Controls;
using DevExpress.XtraTreeList;

// Prevents the Edit Form from being shown depending on the cell data.
private void treeList1_EditFormShowing(object sender, DevExpress.XtraTreeList.EditFormShowingEventArgs e) {
    if (e.Node.GetValue(colCity).Equals("Berlin"))
        e.Allow = false;
}
// Focuses the editor in the Edit Form that corresponds to the column focused in the Tree List.
// Subscribes to an editor's events.
private void treeList1_EditFormPrepared(object sender, DevExpress.XtraTreeList.EditFormPreparedEventArgs e) {
    TreeList treeList = sender as TreeList;
    Control editor = e.BindableControls[treeList.FocusedColumn];
    if (editor != null) {
        editor.Focus();
        ((IContainerControl)e.Panel).ActivateControl(editor);
    }

    TextEdit textEdit = e.BindableControls[colCity] as TextEdit;
    if (textEdit != null)
        textEdit.EditValueChanging += TextEdit_EditValueChanging;
}
private void TextEdit_EditValueChanging(object sender, ChangingEventArgs e) {
    // ...
}
// Unsubscribes from the editor's events.
// Shows a message depending on the clicked button.
private void treeList1_EditFormHidden(object sender, DevExpress.XtraTreeList.EditFormHiddenEventArgs e) {
   TextEdit textEdit = e.BindableControls[colCity] as TextEdit;
    if (textEdit != null)
        textEdit.EditValueChanging -= TextEdit_EditValueChanging;
    if (e.Result == EditFormResult.Update)
        XtraMessageBox.Show("Changes are successfully saved.");

}

VB.NET

Imports DevExpress.XtraEditors
Imports DevExpress.XtraEditors.Controls
Imports DevExpress.XtraTreeList

Private Sub treeList1_EditFormShowing(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.EditFormShowingEventArgs) _
    Handles treeList1.EditFormShowing
    If e.Node.GetValue(colCity).Equals("Berlin") Then
        e.Allow = False
    End If
End Sub
Private Sub treeList1_EditFormPrepared(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.EditFormPreparedEventArgs) _
    Handles treeList1.EditFormPrepared
    Dim treeList As TreeList = TryCast(sender, TreeList)
    Dim editor As Control = e.BindableControls(treeList.FocusedColumn)
    If editor IsNot Nothing Then
        editor.Focus()
        DirectCast(e.Panel, IContainerControl).ActivateControl(editor)
    End If

    Dim textEdit As TextEdit = TryCast(e.BindableControls(colCity), TextEdit)
    If textEdit IsNot Nothing Then
        AddHandler textEdit.EditValueChanging, AddressOf TextEdit_EditValueChanging
    End If
End Sub
Private Sub TextEdit_EditValueChanging(ByVal sender As Object, ByVal e As ChangingEventArgs)
    ' ...
End Sub
Private Sub treeList1_EditFormHidden(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.EditFormHiddenEventArgs) _
    Handles treeList1.EditFormHidden
    Dim textEdit As TextEdit = TryCast(e.BindableControls(colCity), TextEdit)
    If textEdit IsNot Nothing Then
        RemoveHandler textEdit.EditValueChanging, AddressOf TextEdit_EditValueChanging
    End If
    If e.Result = EditFormResult.Update Then
        XtraMessageBox.Show("Changes are successfully saved.")
    End If
End Sub