ASP.NET MVC TreeList Overview

The Telerik UI TreeList HtmlHelper for ASP.NET MVC is a server-side wrapper for the Kendo UI TreeList widget.

The TreeList enables the display of self-referencing tabular data and allows sorting, filtering, and data editing.

• Demo page for the TreeList HtmlHelper

Initializing the TreeList

The following example demonstrates how to define the TreeList.

The TreeList distinguishes the root items based on the ParentId field. If the ParentId is set as .Nullable(true), root items with be items whose ParentId field values are null. If the ParentId is not nullable (.Nullable(false)), root items will be items which have a default value for their data type.

1. Create a new ASP.NET MVC application. If you have installed the Telerik UI for ASP.NET MVC Visual Studio Extensions, create a Telerik UI for ASP.NET MVC application. Name the application KendoGridServerBinding. If you decided not to use the Telerik UI for ASP.NET MVC Visual Studio Extensions, follow the steps from the introductory article to add Telerik UI for ASP.NET MVC to the application.

2. Add a new Entity Framework Data Model. Right-click the ~/Models folder in the solution explorer and pick Add new item. Choose Data > ADO.NET Entity Data Model in the Add New Item dialog. Name the model Northwind.edmx and click Next. This starts the Entity Data Model Wizard.

   

3. Pick the Generate from database option and click Next. Configure a connection to the Northwind database. Click Next.

   

4. Choose the Employees table from the Which database objects do you want to include in your model?. Leave all other options as they are set by default. Click Finish.

   

5. Right-click the ~/Models folder in the solution explorer and add a new EmployeeViewModel class.

Razor

    @(Html.Kendo().TreeList<Kendo.Mvc.Examples.Models.TreeList.EmployeeDirectoryModel>()
        .Name("treelist")
        .Columns(columns =>
        {
            columns.Add().Field(f => f.FirstName).Width(250).Title("First Name");
            columns.Add().Field(e => e.LastName).Title("Last Name");
            columns.Add().Field(e => e.Position);
            columns.Add().Field(e => e.Extension).Title("Ext").Format("{0:#}");
        })
        .DataSource(dataSource => dataSource
            .Read(read => read.Action("Index", "EmployeeDirectory"))
            .Model(m => {
                m.Id(f => f.EmployeeId);
                m.ParentId(f => f.ReportsTo).Nullable(true);
                m.Field(f => f.FirstName);
                m.Field(f => f.LastName);
                m.Field(f => f.ReportsTo);
            })
        )
    )

C#

    public class EmployeeViewModel
    {
        // The Id.
        public int EmployeeID { get; set; }

        public string FirstName { get; set; }

        public string LastName { get; set; }

        // A nullable ParentId.
        public int? ReportsTo { get; set; }

        public string Address { get; set; }

        // This is a case-sensitive property. Define it only if you want to use lazy-loading.
        // If it is not defined, the TreeList will calculate and assign its value on the client.
        public bool hasChildren { get; set; }
    }

C#

 public JsonResult All([DataSourceRequest] DataSourceRequest request)
    {
        var result = GetDirectory().ToTreeDataSourceResult(request,
            e => e.EmployeeId,
            e => e.ReportsTo,
            e => e
        );

        return Json(result, JsonRequestBehavior.AllowGet);
    }

AsyncController

    public async Task<JsonResult> TreeList_Read([DataSourceRequest] DataSourceRequest request)
    {
        var northwind = new NortwindEntities();

        var result = await northwind.Employees.ToTreeDataSourceResultAsync(request,
            employee => employee.EmployeeID,
            employee => employee.ReportsTo,
            employee => e
        );

        return Json(result, JsonRequestBehavior.AllowGet);
    }

1. Build and run the application.

   

Functionality and Features

Feature	Description
Ajax binding	You can bind the TreeList to remote data.
Editing	The TreeList supports various editing modes that allow you to control the way the data is represented.
Paging	Use the built-in paging functionality to paginate the data.
Grouping with aggregates	The TreeList allows you to display built-in aggregate calculations, when the supplied data is grouped.
Excel	The control enables you to export its content to Excel.
PDF	You can export the content of the TreeList to PDF with this built-in functionality.
Column enhancements	The TreeList allows you to set locked (frozen) columns, which remain visible while you scroll the TreeList horizontally.
Scrolling	You can independently control vertical and horizontal scrolling in the component.
Row Selection	The TreeList supports different modes of row selection.
Localization	The control provides localization of its messages.
Accessibility	The TreeList is accessible for screen readers, supports WAI-ARIA attributes, and delivers keyboard shortcuts for faster navigation.

Next Steps

• Getting Started with the TreeList
• Basic Usage of the TreeList HtmlHelper for ASP.NET MVC (Demo)

See Also

• Using the API of the TreeList for ASP.NET MVC (Demo)
• Knowledge Base Section