Serving JSON and HTML formats

Currently, if you take a look at the routes of our application, we have a root route that rendered base.leaf. We also have two resourceful routes, /shopping_lists and /items, which serve JSON data. It would be great if we could respond with the HTML response when users request /shopping_lists from the browser and serve JSON representation of our Shopping Lists when they go to the same /shopping_lists endpoint, but now the request is made from the iOS app. Luckily, we can do this thanks to a powerful feature in Swift called Generics. To make this work, we would need to refactor our resourceful controllers. We also need to use a middleware, which will help us respond with the HTML and JSON responses based on who is making the request. For example, it will respond with an HTML response when a request is made from a browser; otherwise, it will respond with JSON. So, let's begin our refactoring by first creating a middleware.

Creating a middleware

You might be wondering...