blazor-devexpress-dot-blazor-8748265e.md
A collection of root-level or nested context menu items in the Grid, Rich Text Editor, or TreeList component.
Namespace : DevExpress.Blazor
Assembly : DevExpress.Blazor.v25.2.dll
NuGet Package : DevExpress.Blazor
public interface IContextMenuItemCollection :
IReadOnlyList<IContextMenuItem>,
IEnumerable<IContextMenuItem>,
IEnumerable,
IReadOnlyCollection<IContextMenuItem>
The following members return IContextMenuItemCollection objects:
Handle the CustomizeContextMenu event to modify context commands available in the Grid, Rich Text Editor, or TreeList component. In the event handler, use the IContextMenuItemCollection interface members to perform the following operations:
The following code snippet customizes commands available in the header context menu:
@inject NwindDataService NwindDataService
<DxGrid Data="Data"
ShowGroupPanel="true"
ContextMenus="@(GridContextMenus.Header)"
CustomizeContextMenu="CustomizeContextMenu">
<Columns>
<DxGridSelectionColumn />
<DxGridDataColumn FieldName="City" />
<DxGridDataColumn FieldName="Country" />
<DxGridDataColumn FieldName="CustomerName" GroupIndex="0" />
<DxGridDataColumn FieldName="ProductName" />
<DxGridDataColumn FieldName="Total"
UnboundType="GridUnboundColumnType.Decimal"
UnboundExpression="[UnitPrice] * [Quantity]"
DisplayFormat="c"
MinWidth="100" />
</Columns>
</DxGrid>
@code {
BindingList<Invoice> Data { get; set; }
void CustomizeContextMenu(GridCustomizeContextMenuEventArgs args) {
if (args.Context is GridHeaderCommandContext headerContext) {
// Customizes context menu commands for the Total column header
if (headerContext.Column is IGridDataColumn dataColumn && dataColumn.FieldName == "Total") {
args.Items.Remove(GridContextMenuDefaultItemNames.GroupByColumn);
args.Items.Remove(GridContextMenuDefaultItemNames.UngroupColumn);
}
// Customizes context menu commands for the selection column header
if (headerContext.Column is IGridSelectionColumn selectionColumn) {
var isFixed = selectionColumn.FixedPosition != GridColumnFixedPosition.None;
string itemText = isFixed ? "Unfix Column" : "Fix Column to the Left";
var newValue = isFixed ? GridColumnFixedPosition.None : GridColumnFixedPosition.Left;
args.Items.AddCustomItem(itemText, () => {
headerContext.Grid.BeginUpdate();
headerContext.Column.FixedPosition = newValue;
headerContext.Grid.EndUpdate();
});
}
}
}
protected override async Task OnInitializedAsync() {
var invoices = await NwindDataService.GetInvoicesAsync();
Data = new BindingList<Invoice>(invoices.ToList());
}
}
public class Invoice {
public string ShipName { get; set; }
public string ShipAddress { get; set; }
public string ShipCity { get; set; }
public string ShipRegion { get; set; }
public string ShipPostalCode { get; set; }
public string ShipCountry { get; set; }
public string CustomerId { get; set; }
public string CustomerName { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string Region { get; set; }
public string PostalCode { get; set; }
public string Country { get; set; }
public string Salesperson { get; set; }
public int OrderId { get; set; }
public DateTime? OrderDate { get; set; }
public DateTime? RequiredDate { get; set; }
public DateTime? ShippedDate { get; set; }
public string ShipperName { get; set; }
public int ProductId { get; set; }
public string ProductName { get; set; }
public decimal UnitPrice { get; set; }
public short Quantity { get; set; }
public float Discount { get; set; }
public decimal? ExtendedPrice { get; set; }
public decimal? Freight { get; set; }
}
public partial class NwindDataService {
public Task<IEnumerable<Product>> GetProductsAsync(CancellationToken ct = default) {
// Return your data here
}
}
services.AddScoped<NwindDataService>();
The following code snippet operates with item collections in the CustomizeContextMenu event handler:
<DxRichEdit CustomizeContextMenu=OnCustomizeContextMenu />
@code {
void OnCustomizeContextMenu(IContextMenuItemCollection items) {
// Inserts a custom item at the first position in the item collection
var searchItem = items.AddCustomItem(0, "Google Search...", ...);
var openHyperlinkItem = items[RichEditContextMenuItemNames.OpenHyperlink];
openHyperlinkItem.BeginGroup = false;
// Gets the built-in item's position in the item collection
var index = items.IndexOf(openHyperlinkItem);
// Inserts a custom item at the specified position in the main menu's item collection
var showURLItem = items.AddCustomItem(index, "Show URL", ...);
showURLItem.BeginGroup = true;
// Removes built-in items from the item collection
items.Remove(RichEditContextMenuItemNames.CutSelection);
items.Remove(RichEditContextMenuItemNames.CopySelection);
items.Remove(RichEditContextMenuItemNames.Paste);
// Inserts a custom item at the second position in the item collection
var clipboardItem = items.AddCustomItem(1, "Clipboard");
clipboardItem.BeginGroup = true;
// Adds default items to the item collection of the inserted item
clipboardItem.Items.Add(RichEditContextMenuItemNames.CutSelection);
clipboardItem.Items.Add(RichEditContextMenuItemNames.CopySelection);
clipboardItem.Items.Add(RichEditContextMenuItemNames.Paste);
}
}
Run Demo: Context Menu Customization
The following code snippet customizes commands available in header and data row context menus:
@inject EmployeeTaskService EmployeeTaskService
<DxTreeList Data="TreeListData"
KeyFieldName="Id"
ParentKeyFieldName="ParentId"
ContextMenus="@(TreeListContextMenus.Header | TreeListContextMenus.DataRow)"
CustomizeContextMenu="CustomizeContextMenu">
<Columns>
<DxTreeListSelectionColumn Width="80px"/>
<DxTreeListDataColumn FieldName="Name" Caption="Task" />
<DxTreeListDataColumn FieldName="EmployeeName" />
<DxTreeListDataColumn FieldName="StartDate" />
<DxTreeListDataColumn FieldName="DueDate" />
</Columns>
</DxTreeList>
@code {
List<EmployeeTask> TreeListData { get; set; }
protected override void OnInitialized() {
TreeListData = EmployeeTaskService.GenerateData();
}
void CustomizeContextMenu(TreeListCustomizeContextMenuEventArgs args) {
// Customizes context menu commands for the selection column header
if (args.Context is TreeListHeaderCommandContext headerContext) {
if (headerContext.Column is ITreeListSelectionColumn selectionColumn) {
var isFixed = selectionColumn.FixedPosition != TreeListColumnFixedPosition.None;
string itemText = isFixed ? "Unfix Column" : "Fix Column to the Left";
var newValue = isFixed ? TreeListColumnFixedPosition.None : TreeListColumnFixedPosition.Left;
args.Items.AddCustomItem(itemText, () => {
headerContext.TreeList.BeginUpdate();
headerContext.Column.FixedPosition = newValue;
headerContext.TreeList.EndUpdate();
});
}
}
// Adds context menu commands for data rows
if (args.Context is TreeListDataRowCommandContext) {
args.Items.Add(TreeListContextMenuDefaultItemNames.ExpandAll);
args.Items.Add(TreeListContextMenuDefaultItemNames.CollapseAll);
}
}
}
public class EmployeeTask {
public int Id { get; set; }
public int ParentId { get; set; }
public string Name { get; set; }
public string EmployeeName { get; set; }
public DateTime StartDate { get; set; }
public DateTime DueDate { get; set; }
public int Progress { get; set; }
public EmployeeTask() { }
public EmployeeTask(
int id,
int parentId,
string name,
string employeeName,
DateTime startDate,
DateTime dueDate,
int progress
)
{
Id = id;
ParentId = parentId;
Name = name;
EmployeeName = employeeName;
StartDate = startDate;
DueDate = dueDate;
Progress = progress;
}
}
public class EmployeeTaskService {
public List<EmployeeTask> GenerateData() {
return new List<EmployeeTask>() {
new EmployeeTask(1, 0, "Simplify & Clarify Product Messaging", "John Heart", new DateTime(2018, 4, 3), new DateTime(2018, 4, 14), 14),
new EmployeeTask(2, 1, "Prepare Financial Reports", "Samantha Bright", new DateTime(2018, 4, 3), new DateTime(2018, 4, 7), 17),
new EmployeeTask(3, 1, "Prepare Marketing Plan", "Arthur Miller", new DateTime(2018, 4, 7), new DateTime(2018, 4, 14), 11),
new EmployeeTask(4, 0, "Create Action Plan to Improve Customer Engagement", "Robert Reagan", new DateTime(2017, 8, 8), new DateTime(2018, 4, 8), 23),
new EmployeeTask(5, 4, "Update Personnel Files", "Greta Sims", new DateTime(2017, 8, 8), new DateTime(2017, 10, 18), 100),
new EmployeeTask(6, 4, "Review Health Insurance Options", "Brett Wade", new DateTime(2017, 9, 27), new DateTime(2017, 11, 10), 37),
new EmployeeTask(7, 4, "Choose Between PPO and HMO Health Plan", "Sandra Johnson", new DateTime(2017, 12, 13), new DateTime(2018, 3, 23), 17),
new EmployeeTask(8, 4, "Update Google Adwords Strategy", "Ed Holmes", new DateTime(2017, 8, 23), new DateTime(2017, 12, 23), 45),
new EmployeeTask(9, 4, "Create New Brochure Design", "Barb Banks", new DateTime(2018, 1, 3), new DateTime(2018, 3, 14), 17),
new EmployeeTask(10, 4, "Obtain Price Quote for New Brochure", "Kevin Carter", new DateTime(2018, 2, 1), new DateTime(2018, 3, 15), 18),
new EmployeeTask(11, 4, "Brochure Design Review", "Cindy Stanwick", new DateTime(2017, 8, 22), new DateTime(2017, 10, 28), 4),
new EmployeeTask(12, 4, "Review Website Redesign Strategy", "Sammy Hill", new DateTime(2017, 9, 16), new DateTime(2018, 3, 6), 73),
new EmployeeTask(13, 4, "Roll Out New Website", "Davey Jones", new DateTime(2017, 11, 7), new DateTime(2018, 2, 6), 9),
new EmployeeTask(14, 4, "Update Sales/Marketing Strategy", "Victor Norris", new DateTime(2017, 12, 13), new DateTime(2018, 4, 2), 5),
new EmployeeTask(15, 4, "Update Sales/Revenue Report", "Mary Stern", new DateTime(2017, 12, 25), new DateTime(2018, 4, 2), 4),
new EmployeeTask(16, 4, "Direct vs Online Sales Comparison Report", "Robin Cosworth", new DateTime(2018, 1, 2), new DateTime(2018, 3, 20), 14),
new EmployeeTask(17, 4, "Review Sales Report and Approve Modifications", "Kelly Rodriguez", new DateTime(2017, 9, 4), new DateTime(2017, 10, 30), 8),
new EmployeeTask(18, 4, "Update R&D Strategy", "James Anderson", new DateTime(2017, 11, 13), new DateTime(2017, 12, 4), 12),
new EmployeeTask(19, 4, "Discuss Updated R&D Strategy", "Antony Remmen", new DateTime(2017, 10, 29), new DateTime(2017, 12, 31), 14),
new EmployeeTask(20, 4, "Update QA Strategy", "Olivia Peyton", new DateTime(2017, 10, 31), new DateTime(2017, 11, 2), 18),
new EmployeeTask(21, 4, "Schedule Training Events", "Taylor Riley", new DateTime(2017, 11, 19), new DateTime(2018, 4, 7), 21),
new EmployeeTask(22, 4, "Approve Hiring of John Jeffers", "Amelia Harper", new DateTime(2018, 1, 7), new DateTime(2018, 4, 8), 10),
new EmployeeTask(23, 0, "Increase Average Subscription Price", "Wally Hobbs", new DateTime(2017, 8, 9), new DateTime(2017, 9, 13), 96),
new EmployeeTask(24, 23, "Update Non-Compete Agreements", "Brad Jameson", new DateTime(2017, 8, 9), new DateTime(2017, 9, 3), 96),
new EmployeeTask(25, 23, "Update Employee Records with New NDA", "Karen Goodson", new DateTime(2017, 8, 23), new DateTime(2018, 9, 10), 100)
};
}
}
// ...
builder.Services.AddSingleton<EmployeeTaskService>();
See Also