ASP.NET Core DropDownTree Overview

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The DropDownTree 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.

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.

@(Html.Kendo().DropDownTree()
    .Name("dropdowntree")
    .DataTextField("Name")
    .DataValueField("id")
    .DataSource(dataSource => dataSource
        .Read(read => read
            .Action("Read_DropDownTreeData", "Home")
        )
    )
)
    <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>
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);
}

Basic Configuration

The following example demonstrates the basic configuration of the DropDownTree.

    @(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");
                });
        })
    )
    <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.

Next Steps

See Also

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