Note: This guide works with Ruby 2.6+ through Ruby 3.x, with modern Ruby 3.x features highlighted where applicable. Core metaprogramming concepts remain consistent across Ruby versions.
This document has been collaboratively updated and modernized through an interactive process with Claude Code, revised with examples, visual diagrams, and Ruby 3.x compatibility.
NOTE: This post now lives (and kept up to date) on my blog: http://hakunin.com/rails3-load-paths
Do nothing. All files in this dir are eager loaded in production and lazy loaded in development by default.
The normal controller/view flow is to display a view template corresponding to the current controller action, but sometimes we want to change that. We use render in a controller when we want to respond within the current request, and redirect_to when we want to spawn a new request.
The render method is very overloaded in Rails. Most developers encounter it within the view template, using render :partial => 'form' or render @post.comments, but here we'll focus on usage within the controller.