Your First Extension

Let’s create a simple extension that adds a “Hello World” command to Visual Studio.

Create the Project

1. Open Visual Studio 2022
2. Go to File > New > Project
3. Search for “VSIX” and select VSIX Project w/ Command (Community)
4. Name it HelloWorldExtension
5. Click Create

Understanding the Generated Code

The template creates several files. Let’s examine the key ones:

MyCommand.cs

This file contains your command’s logic:

using System;
using Community.VisualStudio.Toolkit;
using Microsoft.VisualStudio.Shell;
using Task = System.Threading.Tasks.Task;

namespace HelloWorldExtension
{
    [Command(PackageIds.MyCommand)]
    internal sealed class MyCommand : BaseCommand<MyCommand>
    {
        protected override async Task ExecuteAsync(OleMenuCmdEventArgs e)
        {
            await VS.MessageBox.ShowWarningAsync(
                "HelloWorldExtension",
                "Hello, Visual Studio!");
        }
    }
}

The key parts are:

• [Command] attribute links this class to a command ID
• BaseCommand<T> provides the command infrastructure
• ExecuteAsync contains your command’s logic

HelloWorldExtensionPackage.cs

This is your extension’s entry point:

using System;
using System.Runtime.InteropServices;
using System.Threading;
using Community.VisualStudio.Toolkit;
using Microsoft.VisualStudio.Shell;
using Task = System.Threading.Tasks.Task;

namespace HelloWorldExtension
{
    [PackageRegistration(UseManagedResourcesOnly = true, AllowsBackgroundLoading = true)]
    [Guid(PackageGuids.HelloWorldExtensionString)]
    [ProvideMenuResource("Menus.ctmenu", 1)]
    public sealed class HelloWorldExtensionPackage : ToolkitPackage
    {
        protected override async Task InitializeAsync(
            CancellationToken cancellationToken,
            IProgress<ServiceProgressData> progress)
        {
            await this.RegisterCommandsAsync();
        }
    }
}

Key attributes:

• [PackageRegistration] - Registers the package with VS
• [ProvideMenuResource] - Links to the command table
• ToolkitPackage - Base class from Community Toolkit

VSCommandTable.vsct

This XML file defines your command’s placement in VS menus:

<Commands package="guidHelloWorldExtensionPackage">
  <Groups>
    <Group guid="guidHelloWorldExtensionPackageCmdSet"
           id="MyMenuGroup"
           priority="0x0600">
      <Parent guid="guidSHLMainMenu" id="IDM_VS_MENU_TOOLS"/>
    </Group>
  </Groups>

  <Buttons>
    <Button guid="guidHelloWorldExtensionPackageCmdSet"
            id="MyCommand"
            priority="0x0100"
            type="Button">
      <Parent guid="guidHelloWorldExtensionPackageCmdSet" id="MyMenuGroup" />
      <Icon guid="guidImages" id="bmpPic1" />
      <Strings>
        <ButtonText>My Command</ButtonText>
      </Strings>
    </Button>
  </Buttons>
</Commands>

This places your command in the Tools menu.

Run the Extension

1. Press F5 to start debugging
2. A new Visual Studio instance (the “Experimental Instance”) opens
3. Go to Tools > My Command
4. You should see a message box saying “Hello, Visual Studio!”

Customize the Command

Let’s make the command more interesting:

protected override async Task ExecuteAsync(OleMenuCmdEventArgs e)
{
    // Get the active document
    var docView = await VS.Documents.GetActiveDocumentViewAsync();

    if (docView?.TextView == null)
    {
        await VS.MessageBox.ShowWarningAsync(
            "HelloWorldExtension",
            "No active document!");
        return;
    }

    // Get the file name
    var fileName = docView.FilePath;

    await VS.MessageBox.ShowAsync(
        "HelloWorldExtension",
        $"Current file: {fileName}");
}

This version displays the current file name instead of a static message.

Next Steps

Now that you have a working extension, learn about the Project Structure to understand all the files in your VSIX project.