Overview

ReActionView is a new ActionView-compatible ERB engine with modern developer experience - re-imagined with Herb::Engine.

It provides seamless integration of Herb's HTML-aware ERB rendering engine into Rails applications, compatible with .html.erb templates but with modern enhancements like HTML validation, better error feedback, developer-friendly debug mode, and more!

The Herb Journey

ReActionView is the practical payoff of a year-long development effort:

• RubyKaigi 2025: Introduced Herb, a new HTML-aware ERB parser built on Prism
• RailsConf 2025: Released developer tools including formatter, linter, and language server
• Rails World 2025: Debuting ReActionView - bringing it all together as a new ERB engine

What is ReActionView?

ReActionView is a new ActionView-compatible ERB engine that enhances Rails template rendering:

• HTML-aware parsing through Herb's advanced ERB parser
• Enhanced error handling with validation overlays in development
• Debug mode for better development experience
• Security improvements with context-aware validation

Key Features

Full ActionView Compatibility

• Seamless replacement for Rails' ERB handler
• Zero-breaking-change migration for existing .html.erb templates
• Preserves Rails conventions, helpers, and asset pipeline integration
• Maintains performance characteristics of standard ERB

Reactive Server-Rendered Components (Coming Soon)

• Bridge the gap between traditional views and modern frontend frameworks
• Enable dynamic UI updates without JavaScript complexity
• Server-driven reactivity that works with Hotwire and Turbo
• Component state management built into the rendering engine

HTML Validation & Security

• Context-aware validation through Herb's security validators
• Template error overlays displayed directly in the browser (in overlay mode)
• Integration with Herb's validation system for better template safety

Enhanced Development Experience

• Visual debugging with element metadata injection in debug mode
• Better error feedback through validation overlays
• Integration with Herb's ecosystem of developer tools

How It Works

1. Template Registration: ReActionView registers itself as a template handler for .html.herb files and optionally for .html.erb files
2. Herb Processing: Templates are processed through the Herb engine instead of standard ERB
3. Enhanced Output: The result includes validation, security checks, and debug information
4. Rails Integration: Output integrates seamlessly with Rails' @output_buffer and HTML safety mechanisms

Rails World 2025 Debut

ReActionView makes its first public appearance at Rails World 2025, representing the culmination of the Herb ecosystem development. This exclusive release demonstrates:

• Enhanced template processing with Herb::Engine integration
• Migration paths for existing Rails applications
• Improved developer experience and debugging capabilities
• Vision for the future of Rails' view layer

Collaboration & Rails Integration

ReActionView is designed as a collaboration opportunity for the Rails community:

• Exploration Initiative: Experimenting with what's possible in the Rails view layer
• Community Feedback: Gathering insights on architecture and developer experience
• Rails Core Integration: Positioning as a potential evolution of Rails' default view layer
• Open Development: Transparent development process with community input

Getting Started

Ready to be part of the future of Rails templates? Check out the installation guide to get started with ReActionView in your Rails application.