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Getting Started with Blazor ComboBox in Blazor WASM App

29 Jun 20267 minutes to read

This section explains how to include the Blazor ComboBox component in a Blazor WebAssembly App using Visual Studio, Visual Studio Code, and the .NET CLI.

Create a new Blazor WebAssembly (Standalone) App

Create a Blazor WebAssembly App using Visual Studio via Microsoft Templates or the Blazor Extension.

Run the following command to create a new Blazor WebAssembly App.

dotnet new blazorwasm -o BlazorApp
cd BlazorApp

Alternatively, create a Blazor WebAssembly App using Visual Studio Code via Microsoft Templates or the Blazor Extension, or the C# Dev Kit extension.

Run the following command to create a new Blazor WebAssembly App.

dotnet new blazorwasm -o BlazorApp
cd BlazorApp

Install the required Blazor packages

Install the Syncfusion.Blazor.DropDowns and Syncfusion.Blazor.Themes NuGet packages. All Syncfusion Blazor packages are available on nuget.org. See the NuGet packages topic for details.

  1. Go to Tools → NuGet Package Manager → Manage NuGet Packages for Solution.
  2. Search the required NuGet packages (Syncfusion.Blazor.DropDowns and Syncfusion.Blazor.Themes) and install them.

Alternatively, you can install the same packages using the Package Manager Console with the following commands.

Install-Package Syncfusion.Blazor.DropDowns -Version 33.2.3
Install-Package Syncfusion.Blazor.Themes -Version 33.2.3

Open the terminal and run the following commands.

dotnet add package Syncfusion.Blazor.DropDowns -v 33.2.3
dotnet add package Syncfusion.Blazor.Themes -v 33.2.3

Open the command prompt and run the following commands.

dotnet add package Syncfusion.Blazor.DropDowns -v 33.2.3
dotnet add package Syncfusion.Blazor.Themes -v 33.2.3

Add import namespaces

After the packages are installed, open the ~/_Imports.razor file and import the Syncfusion.Blazor and Syncfusion.Blazor.DropDowns namespaces.

@using Syncfusion.Blazor
@using Syncfusion.Blazor.DropDowns

Register the Blazor service

Open the Program.cs file in Blazor WebAssembly App and register the Blazor service.

....
using Syncfusion.Blazor;
....
builder.Services.AddSyncfusionBlazor();
....

Add stylesheet and script resources

The theme stylesheet and script can be accessed from NuGet through Static Web Assets. Include the stylesheet and script references in the ~wwwroot/index.html file.

...
<link href="_content/Syncfusion.Blazor.Themes/fluent2.css" rel="stylesheet" />
...
<script src="_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js" type="text/javascript"></script>

Add Blazor ComboBox component

Open a Razor file located in the ~/Pages/*.razor (for example, Home.razor)
and add the Blazor ComboBox component inside the razor file.

@using Syncfusion.Blazor.DropDowns

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

Run the application

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

Open the terminal and run the following command.

dotnet run

Open the command prompt and run the following command.

dotnet run
Blazor ComboBox Component

Binding data source

After initialization, populate the ComboBox with data using the DataSource property. In the following example, a list of objects (with ID and Text fields) is bound to the ComboBox.

@using Syncfusion.Blazor.DropDowns

<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"},
  };
}
Blazor ComboBox with Data Binding

Custom values

The ComboBox supports custom values that are not present in the predefined list. This behavior is enabled by the AllowCustom property. In this mode, the typed text is treated as both the display text and the value, and the custom value is posted with the form on submit.

<SfComboBox TValue="string"  TItem="Games" AllowCustom=true Placeholder="Select a game" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="ID" Text="Text"></ComboBoxFieldSettings>
</SfComboBox>
Blazor ComboBox with Custom Values

Configure the popup list

By default, the popup list width automatically adjusts to the ComboBox input width, and the popup height is 350px. The height and width of the popup list can be customized using the PopupHeight and PopupWidth properties.

<SfComboBox TValue="string" TItem="Games"PopupHeight="350px" PopupWidth="350px" Placeholder="Select a game" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="ID" Text="Text"></ComboBoxFieldSettings>
</SfComboBox>
Customizing popup height and width in Blazor ComboBox

NOTE

View sample in GitHub.

See also

  1. Getting started with Blazor for client-side in .NET Core CLI
  2. Getting started with Blazor for server-side in Visual Studio
  3. Getting started with Blazor for server-side in .NET Core CLI