TreeList HtmlHelper Overview

The Telerik UI TreeList HtmlHelper for ASP.NET Core 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 Core, 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.

    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);
        })
    )
)

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 Core (Demo)
• Server-Side API