# Row behaviors **RadGridView** manages user *mouse* and *keyboard* input over its rows by **GridRowBehavior**. Depending on the row type, **RadGridView** introduces different behaviors, listed on the table below: | Row behavior | Row type | | ------------------------- | -------------------------- | | GridDataRowBehavior | GridViewDataRowInfo | | GridHierarchyRowBehavior | GridViewHierarchyRowInfo | | GridNewRowBehavior | GridViewNewRowInfo | | GridGroupRowBehavior | GridViewGroupRowInfo | | GridFilterRowBehavior | GridViewFilteringRowInfo | | GridHeaderRowBehavior | GridViewTableHeaderRowInfo | | GridDetailViewRowBehavior | GridViewDetailsRowInfo | By implementing a specific custom row behavior, developers can change the default row functionality or supplement the existing one. Let’s start with constructing a hierarchical **RadGridView** and populate it with data. ```C# public RowBehaviorsForm() { InitializeComponent(); //Fill data DataTable items = new DataTable("Items"); items.Columns.Add("Id", typeof(int)); items.Columns.Add("Title", typeof(string)); items.Columns.Add("IsActive", typeof(bool)); DataTable subItems = new DataTable("SubItems"); subItems.Columns.Add("Id", typeof(int)); subItems.Columns.Add("Name", typeof(string)); subItems.Columns.Add("ItemId", typeof(int)); for (int i = 1; i <= 3; i++) { items.Rows.Add(i, "Item" + i, i % 2 == 0); for (int j = 1000; j <= 1005; j++) { subItems.Rows.Add(j, "SubItem" + j, i); } } //Set up grid hierarchy radGridView1.DataSource = items; radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill; GridViewTemplate template = new GridViewTemplate(); template.ReadOnly = true; template.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill; GridViewRelation relation = new GridViewRelation(radGridView1.MasterTemplate, template); relation.ParentColumnNames.Add("Id"); relation.ChildColumnNames.Add("ItemId"); radGridView1.MasterTemplate.Templates.Add(template); radGridView1.Relations.Add(relation); template.ReadOnly = false; template.DataSource = subItems; } ``` ```VB.NET Sub New() InitializeComponent() 'Fill data Dim items As New DataTable("Items") items.Columns.Add("Id", GetType(Integer)) items.Columns.Add("Title", GetType(String)) items.Columns.Add("IsActive", GetType(Boolean)) Dim subItems As New DataTable("SubItems") subItems.Columns.Add("Id", GetType(Integer)) subItems.Columns.Add("Name", GetType(String)) subItems.Columns.Add("ItemId", GetType(Integer)) For i As Integer = 1 To 3 items.Rows.Add(i, "Item" & i, i Mod 2 = 0) For j As Integer = 1000 To 1005 subItems.Rows.Add(j, "SubItem" & j, i) Next Next 'Set up grid hierarchy RadGridView1.DataSource = items RadGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill Dim template As New GridViewTemplate() template.[ReadOnly] = True template.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill Dim relation As New GridViewRelation(RadGridView1.MasterTemplate, template) relation.ParentColumnNames.Add("Id") relation.ChildColumnNames.Add("ItemId") RadGridView1.MasterTemplate.Templates.Add(template) RadGridView1.Relations.Add(relation) template.[ReadOnly] = False template.DataSource = subItems End Sub ``` By default, when the user hits the **Delete** key over a certain row, the row is deleted. We will extend this functionality by notifying the user when he tries to delete a parent row, which **ChildRows** collection is not empty. For this purpose, it is necessary to create a custom grid behavior. To do this, create a new class named **CustomGridHierarchyRowBehavior**. As we are currently using a hierarchical grid, our class should inherit the **GridHierarchyRowBehavior**. Override the **ProcessDeleteKey** method in order to display a MessageBox and proceed with the delete operation after confirmation only:
![WinForms RadGridView Using Custom Behavior](https://www.telerik.com/products/winforms/documentation/assets/19ad31fb9b5d45bedd5e6f234b088c2b/gridview-rows-row-behaviors001.gif) ```C# public class CustomGridHierarchyRowBehavior : GridHierarchyRowBehavior { protected override bool ProcessDeleteKey(KeyEventArgs keys) { if (this.GridControl.CurrentRow.ChildRows.Count > 0) { DialogResult result = MessageBox.Show("The current row has child rows." + "Are you sure you want to delete the selected row?", "Confirmation", MessageBoxButtons.YesNo); if (result == DialogResult.No) { return true; } } return base.ProcessDeleteKey(keys); } } ``` ```VB.NET Public Class CustomGridHierarchyRowBehavior Inherits GridHierarchyRowBehavior Protected Overrides Function ProcessDeleteKey(keys As KeyEventArgs) As Boolean If Me.GridControl.CurrentRow.ChildRows.Count > 0 Then Dim result As DialogResult = MessageBox.Show("The current row has child rows." & "Are you sure you want to delete the selected row?", "Confirmation", MessageBoxButtons.YesNo) If result = DialogResult.No Then Return True End If End If Return MyBase.ProcessDeleteKey(keys) End Function End Class ``` Next we will register this behavior in our grid. Add the following code after populating the grid with data: ```C# //register the custom row behavior BaseGridBehavior gridBehavior = radGridView1.GridBehavior as BaseGridBehavior; gridBehavior.UnregisterBehavior(typeof(GridViewHierarchyRowInfo)); gridBehavior.RegisterBehavior(typeof(GridViewHierarchyRowInfo), new CustomGridHierarchyRowBehavior()); ``` ```VB.NET 'register the custom row behavior Dim gridBehavior As BaseGridBehavior = TryCast(RadGridView1.GridBehavior, BaseGridBehavior) gridBehavior.UnregisterBehavior(GetType(GridViewHierarchyRowInfo)) gridBehavior.RegisterBehavior(GetType(GridViewHierarchyRowInfo), New CustomGridHierarchyRowBehavior()) ``` The next modification we are going to introduce is to override the **OnMouseDownLeft** method and show the context menu for the **GridCheckBoxCellElement**, associated with the mouse location. First, it is necessary to use the grid navigator to process selection of the cell element, positioned at the mouse location. Afterwards, show the context menu for the specific cell: ```C# protected override bool OnMouseDownLeft(MouseEventArgs e) { GridCellElement cellElement = this.GetCellAtPoint(e.Location); if (cellElement != null && cellElement is GridCheckBoxCellElement) { GridRowElement rowElement = cellElement.RowElement; this.Navigator.BeginSelection(this.GetMouseNavigationContext(e)); this.Navigator.Select(rowElement.RowInfo, cellElement.ColumnInfo); this.Navigator.EndSelection(); if (!cellElement.IsInValidState(true)) { cellElement = this.GetCellAtPoint(e.Location); } if (cellElement != null) { GridViewElement.ContextMenuManager.ShowContextMenu(cellElement); } return true; } return base.OnMouseDownLeft(e); } ``` ```VB.NET Protected Overrides Function OnMouseDownLeft(e As MouseEventArgs) As Boolean Dim cellElement As GridCellElement = Me.GetCellAtPoint(e.Location) If cellElement IsNot Nothing AndAlso TypeOf cellElement Is GridCheckBoxCellElement Then Dim rowElement As GridRowElement = cellElement.RowElement Me.Navigator.BeginSelection(Me.GetMouseNavigationContext(e)) Me.Navigator.[Select](rowElement.RowInfo, cellElement.ColumnInfo) Me.Navigator.EndSelection() If Not cellElement.IsInValidState(True) Then cellElement = Me.GetCellAtPoint(e.Location) End If If cellElement IsNot Nothing Then GridViewElement.ContextMenuManager.ShowContextMenu(cellElement) End If Return True End If Return MyBase.OnMouseDownLeft(e) End Function ``` ![WinForms RadGridView Show Context Menu](https://www.telerik.com/products/winforms/documentation/assets/0e78365ef8d5da1115243fb40fba21ae/gridview-rows-row-behaviors002.png) **RadGridView** supports rows/cells navigation by default, using the arrow keys. It is possible to customize this behavior as well. In the **CustomGridHierarchyRowBehavior** class override the **ProcessKey** method and stop the base grid logic for navigation upwards/downwards if the current row belongs to the **MasterTemplate** and its *“IsActive”* cell value is set to *false*: ```C# public override bool ProcessKey(KeyEventArgs keys) { if (keys.KeyCode == Keys.Up || keys.KeyCode == Keys.Down) { DataRowView rowView = this.GridControl.CurrentRow.DataBoundItem as DataRowView; if (rowView != null && this.GridControl.CurrentRow.ViewTemplate == this.MasterTemplate) { if ((bool)rowView.Row["IsActive"] == false) { return true; } } } return base.ProcessKey(keys); } ``` ```VB.NET Public Overrides Function ProcessKey(keys__1 As KeyEventArgs) As Boolean If keys__1.KeyCode = Keys.Up OrElse keys__1.KeyCode = Keys.Down Then Dim rowView As DataRowView = TryCast(Me.GridControl.CurrentRow.DataBoundItem, DataRowView) If rowView IsNot Nothing AndAlso Me.GridControl.CurrentRow.ViewTemplate.Equals(Me.MasterTemplate) Then If CBool(rowView.Row("IsActive")) = False Then Return True End If End If End If Return MyBase.ProcessKey(keys__1) End Function ``` Following the demonstrated approach, developers can customize not only the hierarchy rows, but the new row for example, implementing a custom **GridNewRowBehavior** and registering it for the **GridViewNewRowInfo**. ## See Also * [Adding and Inserting Rows](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/adding-and-inserting-rows) * [Conditional Formatting Rows](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/conditional-formatting-rows) * [Creating custom rows](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/creating-custom-rows) * [Drag and Drop](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/drag-and-drop) * [Formatting Rows](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/formatting-rows) * [GridViewRowInfo](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/gridviewrowinfo) * [Iterating Rows](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/iterating-rows) * [New Row](https://www.telerik.com/products/winforms/documentation/controls/gridview/visual-elements/rows/new-row) * [How to Improve Scrolling Performance with Down Arrow Key in RadGridView](https://www.telerik.com/products/winforms/documentation/knowledge-base/gridview-improve-down-arrow-key-performance)