Rows Reordering in Master-Detail Hierarchy
Consider the case you have a bound RadGridView with master-detail hierarchical data. This article demonstrates how to utilize the RadGridViewDragDropService and implement rows reordering.
Figure 1: Rows reordering in Master-Detail hierarchy
There are several main steps that need to be followed:
Register a custom GridDataRowBehavior which starts the RadGridViewDragDropService when you click with the left mouse button over a child row.
Override the OnMouseDownLeft method of the GridDataRowBehavior and start the service.
Handle the RadDragDropService.PreviewDragStart event in order to indicate that RadGridView can start the drag operation. In the RadDragDropService.PreviewDragOver event you can control on what targets the row being dragged can be dropped on. In the PreviewDragDrop event you can perform the actual reordering of the data bound records. Note that it is important to update the ParentId field of the affected child record. Thus, you will indicate the new parent record to which the dragged record belongs.
BindingList<Level0> parentRecords = new BindingList<Level0>();
BindingList<Level1> childRecords = new BindingList<Level1>();
GridViewRowInfo draggedRow = null;
public RadForm1()
{
InitializeComponent();
FillData();
radGridView1.DataSource = parentRecords;
radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
GridViewTemplate template = new GridViewTemplate();
template.DataSource = childRecords;
template.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
radGridView1.MasterTemplate.Templates.Add(template);
GridViewRelation relation = new GridViewRelation(radGridView1.MasterTemplate);
relation.ChildTemplate = template;
relation.RelationName = "ParentChild";
relation.ParentColumnNames.Add("Id");
relation.ChildColumnNames.Add("ParentId");
radGridView1.Relations.Add(relation);
radGridView1.UseScrollbarsInHierarchy = true;
this.radGridView1.AllowRowReorder = true;
//handle drag and drop events for the grid through the DragDrop service
RadDragDropService svc = this.radGridView1.GridViewElement.GetService<RadDragDropService>();
svc.PreviewDragStart += svc_PreviewDragStart;
svc.PreviewDragDrop += svc_PreviewDragDrop;
svc.PreviewDragOver += svc_PreviewDragOver;
//register the custom row selection behavior
var gridBehavior = this.radGridView1.GridBehavior as BaseGridBehavior;
gridBehavior.UnregisterBehavior(typeof(GridViewDataRowInfo));
gridBehavior.RegisterBehavior(typeof(GridViewDataRowInfo), new RowSelectionGridBehavior());
}
private void svc_PreviewDragStart(object sender, PreviewDragStartEventArgs e)
{
SnapshotDragItem snapshot = e.DragInstance as SnapshotDragItem;
if (snapshot == null)
{
e.CanStart = false;
}
GridDataRowElement draggedRowElement = snapshot.Item as GridDataRowElement;
if (draggedRowElement != null && draggedRowElement.RowInfo != null)
{
e.CanStart = true;
draggedRow = draggedRowElement.RowInfo;
}
else
{
e.CanStart = false;
}
}
private void svc_PreviewDragOver(object sender, RadDragOverEventArgs e)
{
SnapshotDragItem snapshot = e.DragInstance as SnapshotDragItem;
if (snapshot == null)
{
e.CanDrop = false;
}
if (snapshot.Item is GridDataRowElement)
{
e.CanDrop = e.HitTarget is GridDataRowElement || e.HitTarget is GridNewRowElement ||
e.HitTarget is GridTableElement ||
e.HitTarget is GridSummaryRowElement;
}
}
private void svc_PreviewDragDrop(object sender, RadDropEventArgs e)
{
SnapshotDragItem snapshot = e.DragInstance as SnapshotDragItem;
if (snapshot == null)
{
return;
}
var rowElement = snapshot.Item as GridDataRowElement;
if (rowElement == null)
{
return;
}
e.Handled = true;
var dropTarget = e.HitTarget as GridDataRowElement;
var targetGrid = dropTarget.ElementTree.Control as RadGridView;
if (targetGrid == null)
{
return;
}
var dragGrid = draggedRow.ViewTemplate.MasterTemplate.Owner;
if (targetGrid == dragGrid && dropTarget.RowInfo.HierarchyLevel == 1 && draggedRow.HierarchyLevel == 1)
{
e.Handled = true;
Level1 draggedItem = draggedRow.DataBoundItem as Level1;
int targetIndex = childRecords.IndexOf(dropTarget.RowInfo.DataBoundItem as Level1);
Level1 newItem = new Level1(draggedItem.Id, (int)((GridViewHierarchyRowInfo)dropTarget.RowInfo.Parent).Cells["Id"].Value, draggedItem.Name);
GridViewRowInfo targetDataRow = dropTarget.RowInfo;
targetGrid.BeginUpdate();
childRecords.Remove(draggedItem);
childRecords.Insert(targetIndex, newItem);
targetGrid.EndUpdate();
targetGrid.CurrentRow = targetDataRow;
}
}
public class RowSelectionGridBehavior : GridDataRowBehavior
{
protected override bool OnMouseDownLeft(MouseEventArgs e)
{
GridDataRowElement row = this.GetRowAtPoint(e.Location) as GridDataRowElement;
if (row != null)
{
RadGridViewDragDropService svc = this.GridViewElement.GetService<RadGridViewDragDropService>();
svc.AllowAutoScrollColumnsWhileDragging = true;
svc.AllowAutoScrollRowsWhileDragging = true;
svc.Start(new SnapshotDragItem(row));
}
return base.OnMouseDownLeft(e);
}
}
private void FillData()
{
int cnt = 0;
for (int i = 0; i < 10; i++)
{
parentRecords.Add(new Level0(i, "Parent" + i));
for (int j = 0; j < 5; j++)
{
childRecords.Add(new Level1(cnt, i, "Child " + cnt));
cnt++;
}
}
}
public class Level0 : System.ComponentModel.INotifyPropertyChanged
{
public Level0(int id, string title)
{
this.Id = id;
this.Title = title;
}
public int Id
{
get
{
return this._id;
}
set
{
this._id = value;
OnPropertyChanged("Id");
}
}
public string Title
{
get
{
return this._title;
}
set
{
this._title = value;
OnPropertyChanged("Title");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
private int _id;
private string _title;
}
public class Level1 : System.ComponentModel.INotifyPropertyChanged
{
public Level1(int id, int parentId, string name)
{
this.Id = id;
this.ParentId = parentId;
this.Name = name;
}
public int Id
{
get
{
return this._id;
}
set
{
this._id = value;
OnPropertyChanged("Id");
}
}
public int ParentId
{
get
{
return this._parentId;
}
set
{
this._parentId = value;
OnPropertyChanged("ParentId");
}
}
public string Name
{
get
{
return this._name;
}
set
{
this._name = value;
OnPropertyChanged("Name");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
private int _id;
private int _parentId;
private string _name;
}
Private parentRecords As BindingList(Of Level0) = New BindingList(Of Level0)()
Private childRecords As BindingList(Of Level1) = New BindingList(Of Level1)()
Private draggedRow As GridViewRowInfo = Nothing
Public Sub New()
InitializeComponent()
FillData()
RadGridView1.DataSource = parentRecords
RadGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill
Dim template As GridViewTemplate = New GridViewTemplate()
template.DataSource = childRecords
template.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill
RadGridView1.MasterTemplate.Templates.Add(template)
Dim relation As GridViewRelation = New GridViewRelation(RadGridView1.MasterTemplate)
relation.ChildTemplate = template
relation.RelationName = "ParentChild"
relation.ParentColumnNames.Add("Id")
relation.ChildColumnNames.Add("ParentId")
RadGridView1.Relations.Add(relation)
RadGridView1.UseScrollbarsInHierarchy = True
Me.RadGridView1.AllowRowReorder = True
Dim svc As RadDragDropService = Me.RadGridView1.GridViewElement.GetService(Of RadDragDropService)()
AddHandler svc.PreviewDragStart, AddressOf svc_PreviewDragStart
AddHandler svc.PreviewDragDrop, AddressOf svc_PreviewDragDrop
AddHandler svc.PreviewDragOver, AddressOf svc_PreviewDragOver
Dim gridBehavior = TryCast(Me.RadGridView1.GridBehavior, BaseGridBehavior)
gridBehavior.UnregisterBehavior(GetType(GridViewDataRowInfo))
gridBehavior.RegisterBehavior(GetType(GridViewDataRowInfo), New RowSelectionGridBehavior())
End Sub
Private Sub svc_PreviewDragStart(ByVal sender As Object, ByVal e As PreviewDragStartEventArgs)
Dim snapshot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)
If snapshot Is Nothing Then
e.CanStart = False
End If
Dim draggedRowElement As GridDataRowElement = TryCast(snapshot.Item, GridDataRowElement)
If draggedRowElement IsNot Nothing AndAlso draggedRowElement.RowInfo IsNot Nothing Then
e.CanStart = True
draggedRow = draggedRowElement.RowInfo
Else
e.CanStart = False
End If
End Sub
Private Sub svc_PreviewDragOver(ByVal sender As Object, ByVal e As RadDragOverEventArgs)
Dim snapshot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)
If snapshot Is Nothing Then
e.CanDrop = False
End If
If TypeOf snapshot.Item Is GridDataRowElement Then
e.CanDrop = TypeOf e.HitTarget Is GridDataRowElement OrElse TypeOf e.HitTarget Is GridNewRowElement _
OrElse TypeOf e.HitTarget Is GridTableElement OrElse TypeOf e.HitTarget Is GridSummaryRowElement
End If
End Sub
Private Sub svc_PreviewDragDrop(ByVal sender As Object, ByVal e As RadDropEventArgs)
Dim snapshot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)
If snapshot Is Nothing Then
Return
End If
Dim rowElement = TryCast(snapshot.Item, GridDataRowElement)
If rowElement Is Nothing Then
Return
End If
e.Handled = True
Dim dropTarget = TryCast(e.HitTarget, GridDataRowElement)
Dim targetGrid = TryCast(dropTarget.ElementTree.Control, RadGridView)
If targetGrid Is Nothing Then
Return
End If
Dim dragGrid = draggedRow.ViewTemplate.MasterTemplate.Owner
If targetGrid.Equals(dragGrid) AndAlso dropTarget.RowInfo.HierarchyLevel = 1 AndAlso draggedRow.HierarchyLevel = 1 Then
e.Handled = True
Dim draggedItem As Level1 = TryCast(draggedRow.DataBoundItem, Level1)
Dim targetIndex As Integer = childRecords.IndexOf(TryCast(dropTarget.RowInfo.DataBoundItem, Level1))
Dim newItem As Level1 = New Level1(draggedItem.Id, CInt((CType(dropTarget.RowInfo.Parent, _
GridViewHierarchyRowInfo)).Cells("Id").Value), draggedItem.Name)
Dim targetDataRow As GridViewRowInfo = dropTarget.RowInfo
targetGrid.BeginUpdate()
childRecords.Remove(draggedItem)
childRecords.Insert(targetIndex, newItem)
targetGrid.EndUpdate()
targetGrid.CurrentRow = targetDataRow
End If
End Sub
Public Class RowSelectionGridBehavior
Inherits GridDataRowBehavior
Protected Overrides Function OnMouseDownLeft(ByVal e As MouseEventArgs) As Boolean
Dim row As GridDataRowElement = TryCast(Me.GetRowAtPoint(e.Location), GridDataRowElement)
If row IsNot Nothing Then
Dim svc As RadGridViewDragDropService = Me.GridViewElement.GetService(Of RadGridViewDragDropService)()
svc.AllowAutoScrollColumnsWhileDragging = True
svc.AllowAutoScrollRowsWhileDragging = True
svc.Start(New SnapshotDragItem(row))
End If
Return MyBase.OnMouseDownLeft(e)
End Function
End Class
Private Sub FillData()
Dim cnt As Integer = 0
For i As Integer = 0 To 10 - 1
parentRecords.Add(New Level0(i, "Parent" & i))
For j As Integer = 0 To 5 - 1
childRecords.Add(New Level1(cnt, i, "Child " & cnt))
cnt += 1
Next
Next
End Sub
Public Class Level0
Implements System.ComponentModel.INotifyPropertyChanged
Public Sub New(ByVal id As Integer, ByVal title As String)
Me.Id = id
Me.Title = title
End Sub
Public Property Id As Integer
Get
Return Me._id
End Get
Set(ByVal value As Integer)
Me._id = value
OnPropertyChanged("Id")
End Set
End Property
Public Property Title As String
Get
Return Me._title
End Get
Set(ByVal value As String)
Me._title = value
OnPropertyChanged("Title")
End Set
End Property
Public Event PropertyChanged As PropertyChangedEventHandler
Private Event INotifyPropertyChanged_PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
End Sub
Private _id As Integer
Private _title As String
End Class
Public Class Level1
Implements System.ComponentModel.INotifyPropertyChanged
Public Sub New(ByVal id As Integer, ByVal parentId As Integer, ByVal name As String)
Me.Id = id
Me.ParentId = parentId
Me.Name = name
End Sub
Public Property Id As Integer
Get
Return Me._id
End Get
Set(ByVal value As Integer)
Me._id = value
OnPropertyChanged("Id")
End Set
End Property
Public Property ParentId As Integer
Get
Return Me._parentId
End Get
Set(ByVal value As Integer)
Me._parentId = value
OnPropertyChanged("ParentId")
End Set
End Property
Public Property Name As String
Get
Return Me._name
End Get
Set(ByVal value As String)
Me._name = value
OnPropertyChanged("Name")
End Set
End Property
Public Event PropertyChanged As PropertyChangedEventHandler
Private Event INotifyPropertyChanged_PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
End Sub
Private _id As Integer
Private _parentId As Integer
Private _name As String
End Class