TreeList HtmlHelper 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.

The TreeList is part of Telerik UI for ASP.NET MVC, a professional grade UI library with 110+ components for building modern and feature-rich applications. To try it out sign up for a free 30-day trial.

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• Demo page for the TreeList

Initializing the TreeList

The following example demonstrates how to define the TreeList by using the TreeList HtmlHelper.

The TreeList HtmlHelper 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.

    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; }
    }

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

        return Json(result, JsonRequestBehavior.AllowGet);
    }

    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);
    }

@(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);
        })
    )
)

1. Build and run the application.

   

Functionality and Features

• Data operations
  • Ajax binding
  • Editing
  • Paging
  • Grouping with aggregates
• Export options
  • Excel
  • PDF
• More settings
  • Column enhancements
  • Scrolling
  • Row Selection
  • Globalization
  • Accessibility

Events

You can subscribe to all TreeList events. For a complete example on basic TreeList events, refer to the demo on using the events of the TreeList.

    @(Html.Kendo().TreeList<KendoTreeListBinding.Models.EmployeeViewModel>()
        .Name("treelist")
        /* Other configurations. */
        .Events(events => {
            events.DataBinding("onDataBinding");
            events.DataBound("onDataBound");
        })
    )
    <script>
        function onDataBinding(e) {
            // Handle the dataBinding event.
            var treelist = this;
        }

        function onDataBound(e) {
            // Handle the dataBound event.
            var treelist = e.sender;
        }
    </script>

Referencing Existing Instances

To reference an existing Kendo UI TreeList instance, use the jQuery.data() configuration option. Once a reference is established, use the TreeList client-side API to control its behavior.

@(Html.Kendo().TreeList<Kendo.Mvc.Examples.Models.TreeList.EmployeeDirectoryModel>()
    .Name("treelist")
    /* Other configurations. */
)
<script>
    $(function() {
        // The Name() of the TreeList is used to get its client-side instance.
        var treelist = $("#treelist").data("kendoTreeList");
    });
</script>

See Also

• Basic Usage of the TreeList HtmlHelper for ASP.NET MVC (Demo)
• Server-Side API