Getting Started with Dropdown Tree

29 Jan 20244 minutes to read

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

Prerequisites

Create a new Blazor App in Visual Studio

You can create a Blazor Server App or Blazor WebAssembly App using Visual Studio via Microsoft Templates or the Syncfusion Blazor Extension.

Install Syncfusion Blazor Navigations and Themes NuGet in the 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. Alternatively, you can utilize the following package manager command to achieve the same.

Install-Package Syncfusion.Blazor.Navigations -Version 24.2.3
Install-Package Syncfusion.Blazor.Themes -Version 24.2.3

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

Open ~/_Imports.razor file and 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 Server App or Blazor WebAssembly App.

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;
using Syncfusion.Blazor;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddSyncfusionBlazor();

var app = builder.Build();
....
using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Syncfusion.Blazor;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

builder.Services.AddSyncfusionBlazor();
await builder.Build().RunAsync();
....

Add stylesheet and script resources

The theme stylesheet and script can be accessed from NuGet through Static Web Assets. Reference the stylesheet and script in the <head> of the main page as follows:

  • For .NET 6 Blazor Server app, include it in ~/Pages/_Layout.cshtml file.

  • For .NET 7 Blazor Server app, include it in the ~/Pages/_Host.cshtml file.

  • For Blazor WebAssembly app, include it in the ~/index.html file.

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

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 Blazor Dropdown Tree component

Add the Syncfusion Blazor Dropdown Tree component in the ~/Pages/Index.razor file. The TValue parameter specifies the type of the Value property, while TItem specifies the model class for the DataSource property.

@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.