Revit .NET Plugin Template (Cursor)

A minimal .NET 8 class library template for developing Revit plugins with Design Automation API support and debugging capabilities in Visual Studio Code with Cursor. This template is designed for automation workflows and cloud-based Revit processing using Autodesk Platform Services.

Video

https://www.youtube.com/watch?v=hnjMVlEDR_k

Prerequisites

• .NET 8.0 SDK or later
• Revit 2025 or later
• Cursor IDE
• Design Automation Bridge for local testing

Quick Setup

1. Configure Revit Paths

You need to update the Revit paths to match your installation:

In RevitPlugin.csproj (for assembly references):

<!-- Edit this path to match your Revit executable path -->
<RevitPath>C:\Program Files\Autodesk\Revit 2025</RevitPath>

<!-- Edit this path if you have Design Automation Bridge installed locally -->
<DesignAutomationBridgePath>C:\ProgramData\Autodesk\Revit\Addins\2025</DesignAutomationBridgePath>

<!-- Edit this path to match your Revit Addins path -->
<RevitAddinsPath>C:\ProgramData\Autodesk\Revit\Addins\2025</RevitAddinsPath>

Common Revit installation paths:

• Revit 2025: C:\Program Files\Autodesk\Revit 2025
• Revit 2024: C:\Program Files\Autodesk\Revit 2026

2. Build the Project

Open a terminal in the project directory and run:

dotnet build -c Debug -p:Platform=x64

The DLL will be created in bin\Debug\RevitPlugin.dll

Note: The build process automatically updates the .addin file with the correct assembly path using UpdateAddinPath.ps1.

3. Debug in Cursor/VS Code

1. Set breakpoints in Commands.cs (e.g., in the SampleMethod)
2. Copy the .addin file to your Revit Addins folder (automatic in Debug builds)
3. Start Revit manually
4. In Cursor/VS Code, press F5 to attach debugger
5. Select the Revit.exe process when prompted
6. Your plugin will load automatically with Revit

Your breakpoints will be hit when the Design Automation events trigger!

Automation API Overview

This template is specifically designed for Design Automation workflows:

• Implements IExternalDBApplication for database-level operations
• No UI components (suitable for headless Revit execution)
• Includes DesignAutomationBridge for cloud automation support
• Event-driven architecture with DesignAutomationReadyEvent

Debugging Configuration

The template includes debugging configuration in .vscode/launch.json that attaches to the Revit process.

Project Structure

RevitPlugin/
├── RevitPlugin.csproj        # Project configuration
├── Commands.cs               # Main plugin implementation
├── RevitPlugin.addin         # Revit add-in manifest
├── UpdateAddinPath.ps1       # Build script for updating paths
├── package-bundle.ps1        # Packaging script for deployment
├── .vscode/
│   ├── launch.json          # Debug configuration
│   └── tasks.json           # Build tasks
├── .gitignore               # Git ignore rules
├── LICENSE                  # License file
└── README.md                # This file

Customization

Modifying the Main Plugin Logic

Edit the HandleDesignAutomationReadyEvent method in Commands.cs:

private void HandleDesignAutomationReadyEvent(object? sender, DesignAutomationReadyEventArgs e)
{
    LogTrace("Design Automation Ready event triggered...");
    e.Succeeded = true;
    
    // Add your custom logic here
    ProcessRevitModel();
}

private void ProcessRevitModel()
{
    // Access the Revit document
    Document doc = e.DesignAutomationData.RevitDoc;
    
    // Perform your operations
    using (Transaction trans = new Transaction(doc, "My Operation"))
    {
        trans.Start();
        // Your code here
        trans.Commit();
    }
}

Changing Target Revit Version

1. Update the <RevitPath> in the project file
2. Update the <RevitAddinsPath> to match the version year
3. Ensure the <TargetFramework> is compatible with your Revit version

Troubleshooting

"Could not load file or assembly" error

• Ensure Revit path is correct in the project file
• Verify you're building for x64 platform
• Check that the Revit API version matches your Revit installation

Breakpoints not hitting

• Ensure you're running in Debug configuration
• Verify the .addin file is in the correct Revit Addins folder
• Check that the assembly path in the .addin file is correct
• Try rebuilding the project

Design Automation Bridge issues

• Ensure DesignAutomationBridge.dll is referenced correctly
• Set <Private>True</Private> for the bridge reference to include it in output
• Verify the bridge path in the project file

Plugin not loading

• Check the Revit journal file for errors
• Verify the AddInId in the .addin file is unique
• Ensure the .addin file XML is valid

Additional Resources

• Revit API Developer's Guide
• Automation API for Revit
• Autodesk Platform Services
• Revit API Forum

License

This sample is licensed under the terms of the MIT License. Please see the LICENSE file for full details.

Written by

João Martins in/jpornelas, Autodesk Platform Services