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ASP.NET Core DropDownTree Overview

The Telerik UI DropDownTree TagHelper and HtmlHelper for ASP.NET Core are server-side wrappers for the Kendo UI DropDownTree widget.

The DropDownTree represents an editor of hierarchical data, rendered in a tree-like structure, which provides multiple selection option and custom nodes.

Initializing the DropDownTree

The following example demonstrates how to define the DropDownTree.

Razor
@(Html.Kendo().DropDownTree()
    .Name("dropdowntree")
    .DataTextField("Name")
    .DataValueField("id")
    .DataSource(dataSource => dataSource
        .Read(read => read
            .Action("Read_DropDownTreeData", "Home")
        )
    )
)
Razor
    <kendo-dropdowntree datatextfield="Name" datavaluefield="id" name="dropdowntree"  style="width: 100%">
        <hierarchical-datasource>
            <schema>
                <hierarchical-model id="id"></hierarchical-model>
            </schema>
            <transport>
                <read url="@Url.Action("Remote_DropDownTreeData", "Home")" />
            </transport>
        </hierarchical-datasource>
    </kendo-dropdowntree>
C#
public static IList<HierarchicalViewModel> GetHierarchicalData()
{
    var result = new List<HierarchicalViewModel>()
    {
        new HierarchicalViewModel() { ID = 1, ParentID = null, HasChildren = true, Name = "Parent item" },
        new HierarchicalViewModel() { ID = 2, ParentID = 1, HasChildren = true, Name = "Parent item" },
        new HierarchicalViewModel() { ID = 3, ParentID = 1, HasChildren = false, Name = "Item" },
        new HierarchicalViewModel() { ID = 4, ParentID = 2, HasChildren = false, Name = "Item" },
        new HierarchicalViewModel() { ID = 5, ParentID = 2, HasChildren = false, Name = "Item" }
    };

    return result;
}

public IActionResult Read_DropDownTreeData(int? id)
{
    var result = GetHierarchicalData()
        .Where(x => id.HasValue ? x.ParentID == id : x.ParentID == null)
        .Select(item => new {
            id = item.ID,
            Name = item.Name,
            hasChildren = item.HasChildren
        });

    return Json(result);
}

Starting with the 2024 Q3 release, the HtmlHelper version of the component supports declarative initialization.

Basic Configuration

The following example demonstrates the basic configuration of the DropDownTree.

Razor
    @(Html.Kendo().DropDownTree()
        .Name("dropdowntree")
        .Items(dropdowntree =>
        {
            dropdowntree.Add().Text("My Web Site")
                .SpriteCssClasses("folder")
                .Expanded(true)
                .Items(root =>
                {
                    root.Add().Text("images")
                        .Expanded(true)
                        .SpriteCssClasses("folder")
                        .Items(images =>
                        {
                            images.Add().Text("logo.png")
                                .SpriteCssClasses("image");
                        });

                    root.Add().Text("resources")
                        .Expanded(true)
                        .SpriteCssClasses("folder")
                        .Items(resources =>
                        {
                            resources.Add().Text("pdf")
                                .Expanded(true)
                                .SpriteCssClasses("folder")
                                .Items(pdf =>
                                {
                                    pdf.Add().Text("prices.pdf")
                                        .SpriteCssClasses("pdf");
                                });

                            resources.Add().Text("zip")
                                .SpriteCssClasses("folder");
                        });

                    root.Add().Text("about.html")
                        .SpriteCssClasses("html");

                    root.Add().Text("index.html")
                        .SpriteCssClasses("html");
                });
        })
    )
Razor
    <kendo-dropdowntree name="dropdowntree">
        <items>
            <dropdowntree-item expanded="true" text="My Web Site" sprite-css-class="folder">
                <items>
                    <dropdowntree-item expanded="true" text="images" sprite-css-class="folder">
                        <items>
                            <dropdowntree-item text="logo.png" sprite-css-class="image">
                            </dropdowntree-item>
                        </items>
                    </dropdowntree-item>
                </items>
            </dropdowntree-item>
            <dropdowntree-item expanded="true" text="resources" sprite-css-class="folder">
                <items>
                    <dropdowntree-item expanded="true" text="pdf" sprite-css-class="folder">
                        <items>
                            <dropdowntree-item text="prices.pdf" sprite-css-class="pdf">
                            </dropdowntree-item>
                            <dropdowntree-item text="zip" sprite-css-class="folder">
                                <items>
                                    <dropdowntree-item  text="about.html" sprite-css-class="html">
                                    </dropdowntree-item>
                                    <dropdowntree-item text="index.html" sprite-css-class="html">
                                    </dropdowntree-item>
                                </items>
                            </dropdowntree-item>
                        </items>
                    </dropdowntree-item>
                </items>
            </dropdowntree-item>
        </items>
    </kendo-dropdowntree>

Functionality and Features

Feature	Description
Data binding	The DropDownTree supports different data binding approaches.
Checkboxes	You can add checkboxes to the DropDownTree's items.
Filtering	You are able to filter the displayed DropDownTree items by their text value.
Items	You can configure different options for the items of the component.
Templates	The DropDownTree supports customizing its look through templates.
Accessibility	The DropDownTree is accessible by screen readers and provides WAI-ARIA, Section 508, WCAG 2.2, and keyboard support.

ASP.NET Core DropDownTree Overview

Initializing the DropDownTree

Basic Configuration

Functionality and Features

Next Steps

See Also