IContextMenuItemCollection.IndexOf(IContextMenuItem) Method

Returns the specified item’s position within the item collection.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v25.2.dll

NuGet Package: DevExpress.Blazor

Declaration

int IndexOf(
    IContextMenuItem item
)

Parameters

Name	Type	Description
item	IContextMenuItem	Context menu item.

Returns

Type	Description
Int32	The item’s position in the item collection. -1 if the collection does not contain the specified item.

Remarks

Handle the CustomizeContextMenu event to modify context commands available in the Grid, Rich Text Editor, or TreeList component. In the event handler, call the IndexOf method to obtain a context menu item’s position.

Grid Example

The following code snippet adds the Clear Grouping item after the Ungroup Column command:

Razor

@inject WeatherForecastService ForecastService

<DxGrid Data="@Data"
        ShowGroupPanel="true"
        ContextMenus="GridContextMenus.All"
        CustomizeContextMenu="CustomizeContextMenu">
    <Columns>
        <DxGridDataColumn FieldName="Date" DisplayFormat="D" />
        <DxGridDataColumn FieldName="TemperatureC" Caption="@("Temp. (\x2103)")" Width="120px" />
        <DxGridDataColumn FieldName="TemperatureF" Caption="@("Temp. (\x2109)")" Width="120px" />
        <DxGridDataColumn FieldName="Forecast" GroupIndex="0" />
        <DxGridDataColumn FieldName="CloudCover" />
    </Columns>
</DxGrid>

@code {
    object Data { get; set; }

    protected override void OnInitialized() {
        Data = ForecastService.GetForecast();
    }
    void CustomizeContextMenu(GridCustomizeContextMenuEventArgs args) {
        if (args.Context is GridHeaderCommandContext) {
            var ungroupItem = args.Items[GridContextMenuDefaultItemNames.UngroupColumn];
            if (ungroupItem != null) {
                var position = args.Items.IndexOf(ungroupItem);
                var newItem = args.Items.Add(position, GridContextMenuDefaultItemNames.ClearGrouping);
                newItem.BeginGroup = true;
                ungroupItem.BeginGroup = false;
            }
        }
    }
}

WeatherForecast

using System;

public class WeatherForecast {
    public DateTime Date { get; set; }
    public int TemperatureC { get; set; }
    public double TemperatureF => Math.Round((TemperatureC * 1.8 + 32), 2);
    public string Forecast { get; set; }
    public string CloudCover { get; set; }
    public bool Precipitation { get; set; }
}

WeatherForecastService

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class WeatherForecastService {
    private List<WeatherForecast> Forecast { get; set; }

    private static string[] CloudCover = new[] {
        "Sunny", "Partly cloudy", "Cloudy", "Storm"
    };

    Tuple<int, string>[] ConditionsForForecast = new Tuple<int, string>[] {
        Tuple.Create( 22 , "Hot"),
        Tuple.Create( 13 , "Warm"),
        Tuple.Create( 0 , "Cold"),
        Tuple.Create( -10 , "Freezing")
    };

    public WeatherForecastService() {
        Forecast = CreateForecast();
    }

    private List<WeatherForecast> CreateForecast() {
        var rng = new Random();
        DateTime startDate = DateTime.Now;
        return Enumerable.Range(1, 15).Select(index => {
            var temperatureC = rng.Next(-10, 30);
            return new WeatherForecast {
                Date = startDate.AddDays(index),               
                TemperatureC = temperatureC,
                CloudCover = CloudCover[rng.Next(0, 4)],
                Precipitation = Convert.ToBoolean(rng.Next(0, 2)),
                Forecast = ConditionsForForecast.First(c => c.Item1 <= temperatureC).Item2
            };
        }).ToList();
    }

    public IEnumerable<WeatherForecast> GetForecast() {
        return Forecast.ToArray();
    }
    // ...
}

Program.cs

// ...
builder.Services.AddSingleton<WeatherForecastService>();

Rich Text Editor Example

The following code snippet adds a custom Show URL item before the Open Hyperlink item if a hyperlink is selected:

<DxRichEdit CustomizeContextMenu=OnCustomizeContextMenu />

@code {
    DxPopup popup;
    Selection selection;
    string link;
    // ...
    async Task OnCustomizeContextMenu(IContextMenuItemCollection items) {
        var hyperlinks = await selection.ActiveSubDocument.Hyperlinks.GetAllAsync();
        var hyperlink = hyperlinks.SingleOrDefault(h => Enumerable.Range(h.Interval.Start, h.Interval.Length).Contains(selection.CaretPosition));
        link = hyperlink?.Url;
        if (!string.IsNullOrEmpty(link)) {
            var openHyperlinkItem = items[RichEditContextMenuItemNames.OpenHyperlink];
            openHyperlinkItem.BeginGroup = false;
            var index = items.IndexOf(openHyperlinkItem);
            var showURLItem = items.AddCustomItem(index, "Show URL");
            showURLItem.Click = async () => {
                if (popup is not null)
                    await popup.ShowAsync();
            };
            showURLItem.BeginGroup = true;
        }
    }
}

Run Demo: Context Menu Customization

TreeList Example

The following code sample adds Expand All/Collapse All items to the header context menu:

Razor

@inject EmployeeTaskService EmployeeTaskService

<DxTreeList Data="TreeListData"
            KeyFieldName="Id"
            ParentKeyFieldName="ParentId"
            ContextMenus="TreeListContextMenus.Header"
            CustomizeContextMenu="CustomizeContextMenu">
    <Columns>
        <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) {
         var newItem = args.Items.Add(TreeListContextMenuDefaultItemNames.CollapseAll);
         var itemPosition = args.Items.IndexOf(newItem);
         args.Items.Add(itemPosition, TreeListContextMenuDefaultItemNames.ExpandAll).BeginGroup = true;
    }
}

EmployeeTask.cs

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;
    }
}

EmployeeTaskService.cs

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)
        };
    }
}

Program.cs

// ...
builder.Services.AddSingleton<EmployeeTaskService>();