Getting Started with Blazor Dropdown Tree Component in Web App

3 Jan 20256 minutes to read

This section briefly explains about how to include Blazor Dropdown Tree component in your Blazor Web App using Visual Studio.

Prerequisites

Create a new Blazor Web App

You can create a Blazor Web App using Visual Studio 2022 via Microsoft Templates or the Syncfusion® Blazor Extension.

You need to configure the corresponding Interactive render mode and Interactivity location while creating a Blazor Web Application.

Install Syncfusion® Blazor Navigations and Themes NuGet in the Blazor Web App

To add Blazor Dropdown Tree component in the app, open the NuGet package manager in Visual Studio (Tools → NuGet Package Manager → Manage NuGet Packages for Solution), search and install Syncfusion.Blazor.Navigations and Syncfusion.Blazor.Themes.

If you utilize WebAssembly or Auto render modes in the Blazor Web App need to be install Syncfusion® Blazor components NuGet packages within the client project.

Alternatively, you can utilize the following package manager command to achieve the same.

Install-Package Syncfusion.Blazor.Navigations -Version 28.1.33
Install-Package Syncfusion.Blazor.Themes -Version 28.1.33

NOTE

Syncfusion® Blazor components are available in nuget.org. Refer to NuGet packages topic for available NuGet packages list with component details.

Register Syncfusion® Blazor Service

Interactive Render Mode Description
WebAssembly or Auto Open ~/_Imports.razor file from the client project.
Server Open ~/_import.razor file, which is located in the Components folder.

Import the Syncfusion.Blazor and Syncfusion.Blazor.Navigations namespace.

@using Syncfusion.Blazor
@using Syncfusion.Blazor.Navigations

Now, register the Syncfusion® Blazor Service in the ~/Program.cs file of your Blazor Web App.

If the Interactive Render Mode is set to WebAssembly or Auto, you need to register the Syncfusion® Blazor service in both ~/Program.cs files of your Blazor Web App.

...
...
using Syncfusion.Blazor;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents()
    .AddInteractiveWebAssemblyComponents();
builder.Services.AddSyncfusionBlazor();

var app = builder.Build();
....
...
using Syncfusion.Blazor;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.Services.AddSyncfusionBlazor();

await builder.Build().RunAsync();

If the Interactive Render Mode is set to Server, your project will contain a single ~/Program.cs file. So, you should register the Syncfusion® Blazor Service only in that ~/Program.cs file.

...
using Syncfusion.Blazor;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents();
builder.Services.AddSyncfusionBlazor();

var app = builder.Build();
....

Add stylesheet and script resources

The theme stylesheet and script can be accessed from NuGet through Static Web Assets. Include the stylesheet reference in the <head> section and the script reference at the end of the <body> in the ~/Components/App.razor file as shown below:

<head>
    ....
    <link href="_content/Syncfusion.Blazor.Themes/bootstrap5.css" rel="stylesheet" />
</head>
....
<body>
    ....
    <script src="_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js" type="text/javascript"></script>
</body>

NOTE

Check out the Blazor Themes topic to discover various methods (Static Web Assets, CDN, and CRG) for referencing themes in your Blazor application. Also, check out the Adding Script Reference topic to learn different approaches for adding script references in your Blazor application.

Add Syncfusion® Blazor Dropdown Tree component

Add the Syncfusion® Blazor Dropdown Tree component in .razor file inside the Pages folder. The TValue parameter specifies the type for the Value property, while TItem specifies the model class for the DataSource property. If an interactivity location as Per page/component in the web app, define a render mode at top of the component, as follows:

Interactivity location RenderMode Code
Per page/component Auto @rendermode InteractiveAuto
  WebAssembly @rendermode InteractiveWebAssembly
  Server @rendermode InteractiveServer
  None —

NOTE

If an Interactivity Location is set to Global and the Render Mode is set to Auto or WebAssembly or Server, the render mode is configured in the App.razor file by default.

@* desired render mode define here *@
@rendermode InteractiveAuto
@using Syncfusion.Blazor.Navigations

<SfDropDownTree TItem="EmployeeData" TValue="string" Placeholder="Select an employee" Width="500px">
    <DropDownTreeField TItem="EmployeeData" DataSource="Data" Id="Id" Text="Name" HasChildren="HasChild" ParentID="PId"></DropDownTreeField>
</SfDropDownTree>

@code {
    List<EmployeeData> Data = new List<EmployeeData>
    {
        new EmployeeData() {Id="1", Name = "Steven Buchanan", HasChild=true, Expanded=true},
        new EmployeeData() {Id="2", PId="1", Name = "Laura Callahan", HasChild=true},
        new EmployeeData() {Id="3", PId="2", Name = "Andrew Fuller", HasChild=true },
        new EmployeeData() {Id="4", PId="3", Name = "Anne Dodsworth" },
        new EmployeeData() {Id="5", PId="3", Name = "Lilly" }
    };
    public class EmployeeData
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public bool HasChild { get; set; }
        public bool Expanded { get; set; }
        public string PId { get; set; }
    }
}
Blazor Dropdown Tree Component

NOTE

View Sample in GitHub.