Chapter 3
Controllers

By now, you should have a loose grasp of how Phoenix applications work. You know that a typical request starts at an endpoint, flows through a router, and then flows into a controller. You should be starting to appreciate that web programming is a functional problem, and that it’s natural to represent it using a functional language.

The “Hello, World” application we built in the previous chapter was a toy. It was the appropriate way to introduce you to Phoenix and the basics, but we’re going to abandon it now so we can grapple with code organization and problem solving. For the rest of the book, we’re going to work in a new project, and we’ll continue developing it through to the end. Before we get started, though, let’s take a deeper look at how controllers work. In addition, we’ll introduce all of the things controllers touch, including views, templates, and contexts.