What code runs when you request a page from a Ruby on Rails application?
Here is an annotated trace showing every method call within Rails and its dependencies. It is for an example application that loads a blog post from the database and renders a page containing the post's title.
If you have used Rails before you may be familiar with creating controllers which subclass ActionController::Base. This provides lots of functionality for your controllers including parameter passing and template rendering.
Within Rails, ActionController::Metal sits above ActionController::Base. Using Metal directly can sometimes bring performance benefits.
Created by Chris Zetter in a tribute to Rails and its many contributors.
Read out more about how the trace was made.
You can see the code that powers this page and suggest resources to link to on GitHub.