Getting Started with Blazor ComboBox Component in Web App

31 Jan 202510 minutes to read

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

Prerequisites

System requirements for Blazor components

Create a new Blazor Web App in Visual Studio

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 DropDowns and Themes NuGet in the Blazor Web App

To add Blazor ComboBox 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.DropDowns 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.

Package Manager
Install-Package Syncfusion.Blazor.DropDowns -Version 28.2.3
Install-Package Syncfusion.Blazor.Themes -Version 28.2.3

NOTE

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

Create a new Blazor Web App in Visual Studio Code

You can create a Blazor Web App using Visual Studio Code 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.

For example, in a Blazor Web App with the Auto interactive render mode, use the following commands.

Blazor Web App
dotnet new blazor -o BlazorWebApp -int Auto
cd BlazorWebApp
cd BlazorWebApp.Client

NOTE

For more information on creating a Blazor Web App with various interactive modes and locations, refer to this link.

Install Syncfusion^® Blazor DropDowns and Themes NuGet in the App

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.

Press Ctrl+` to open the integrated terminal in Visual Studio Code.
Ensure you’re in the project root directory where your .csproj file is located.
Run the following command to install a Syncfusion.Blazor.DropDowns and Syncfusion.Blazor.Themes NuGet package and ensure all dependencies are installed.

Package Manager
dotnet add package Syncfusion.Blazor.DropDowns -v 28.2.3
dotnet add package Syncfusion.Blazor.Themes -v 28.2.3
dotnet restore

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.DropDowns namespace.

~/_Imports.razor
@using Syncfusion.Blazor
@using Syncfusion.Blazor.DropDowns

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.

Server(~/_Program.cs)
Client(~/_Program.cs)
...
...
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.

~/_Program.cs
...
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 ComboBox component

Add the Syncfusion^® Blazor ComboBox component in .razor file inside the Pages folder. 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.

RAZOR

@* desired render mode define here *@
@rendermode InteractiveAuto

RAZOR
<SfComboBox TValue="string" TItem="string" Placeholder="Select a game"></SfComboBox>

Press Ctrl+F5 (Windows) or ⌘+F5 (macOS) to launch the application. This will render the Syncfusion^® Blazor ComboBox component in your default web browser.

Binding data source

After initializing, populate the ComboBox with data using the DataSource property. Here, an array of string values is passed to the ComboBox component.

RAZOR
<SfComboBox TValue="string" TItem="Games" Placeholder="Select a game" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="ID" Text="Text"></ComboBoxFieldSettings>
</SfComboBox>

@code {
  public class Games
  {
    public string ID { get; set; }
    public string Text { get; set; }
  }
  List<Games> LocalData = new List<Games> {
    new Games() { ID= "Game1", Text= "American Football" },
    new Games() { ID= "Game2", Text= "Badminton" },
    new Games() { ID= "Game3", Text= "Basketball" },
    new Games() { ID= "Game4", Text= "Cricket" },
    new Games() { ID= "Game5", Text= "Football" },
    new Games() { ID= "Game6", Text= "Golf" },
    new Games() { ID= "Game7", Text= "Hockey" },
    new Games() { ID= "Game8", Text= "Rugby"},
    new Games() { ID= "Game9", Text= "Snooker" },
    new Games() { ID= "Game10", Text= "Tennis"},
  };
}

Custom values

The ComboBox allows the users to give input as custom value, which is not required to present in predefined set of values. By default, this support is enabled by AllowCustom property. In this case, both text field and value field are considered as same. The custom value will be sent to post back handler when a form is about to be submitted.

RAZOR
<SfComboBox TValue="string"  TItem="Games" AllowCustom=true Placeholder="Select a game" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="ID" Text="Text"></ComboBoxFieldSettings>
</SfComboBox>

By default, the width of the popup list automatically adjusts according to the ComboBox input element’s width, and the height of the popup list has 350px. The height and width of the popup list can also be customized using the PopupHeight and PopupWidth properties respectively.

RAZOR
<SfComboBox TValue="string" TItem="Games"PopupHeight="350px" PopupWidth="350px" Placeholder="Select a game" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="ID" Text="Text"></ComboBoxFieldSettings>
</SfComboBox>

NOTE

View Sample in GitHub.

Getting Started with Blazor ComboBox Component in Web App

Prerequisites

Create a new Blazor Web App in Visual Studio

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

Create a new Blazor Web App in Visual Studio Code

Install Syncfusion® Blazor DropDowns and Themes NuGet in the App

Register Syncfusion® Blazor Service