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TreeMap in Razor Pages

Razor Pages is an alternative to the MVC pattern that makes page-focused coding easier and more productive. This approach consists of a cshtml file and a cshtml.cs file (by design, the two files have the same name).

You can seamlessly integrate the Telerik UI TreeMap for ASP.NET Core in Razor Pages applications.

This article describes how to configure the TreeMap component in a Razor Pages scenario.

For the complete project, refer to the TreeMap in Razor Pages example.

Getting Started

To bind the TreeMap to a data set received from a remote endpoint within a Razor Pages application, follow the next steps:

  1. Specify the Read request URL in the DataSource configuration. The URL must refer to the method name in the PageModel. The Model configuration must contain the definition for Children—the name of the Model property that stores the collection of child items.

        @model IndexModel
            .DataSource(dataSource => dataSource
                .Read(r => r.Url("/Index?handler=ReadOptional"))
                .Model(m => m.Children("Items"))
        @model IndexModel
        <kendo-treemap name="treeMap">
                    <read url="/Index?handler=ReadOptional" />
                    <hierarchical-model children="Items"></hierarchical-model>
            <!--Other configuration-->
  2. Add an AntiForgeryToken at the top of the page.

        @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
  3. Send the AntiForgeryToken with the Read request.

            function forgeryToken() {
                return kendo.antiForgeryTokens();

    Additional parameters can also be supplied.

            function forgeryToken() {
                return {
                    __RequestVerificationToken: kendo.antiForgeryTokens().__RequestVerificationToken,
                    additionalParameter: "test"
  4. Within the cshtml.cs file, add a handler method for the Read operation that returns the dataset.

        public static List<Population> TreeMapItems;
        public void OnGet()
            if (TreeMapItems == null)
                // Populate the "TreeMapItems" collection with data.
                TreeMapItems = new List<Population>();
                Population country1 = new Population("Country1", 4833722, new List<Population>());
                country1.Items.Add(new Population("City1", 212113, null));
                Population country2 = new Population("Country2", 735132, new List<Population>());
                country2.Items.Add(new Population("City2_1", 300950, null));
                country2.Items.Add(new Population("City2_2", 20200, null));
        public JsonResult OnPostReadOptional()
            return new JsonResult(TreeMapItems);
        public class Population
            public Population(string name, int value, List<Population> items)
                Name = name;
                Value = value;
                Items = items;
            public string Name { get; set; }
            public int Value { get; set; }
            public List<Population> Items { get; set; }

See Also

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