Due to the sparse signatures of HTTP handler functions, it may seem tricky to add state to a handler. For example, there are a variety of ways to include a database connection. Two approaches to doing this are to pass in the state via closures, which is useful for achieving flexibility on a single handler, or by using a structure.
This recipe will demonstrate both. We'll use a struct controller to store a storage interface and create two routes with a single handler that are modified by an outer function.