vapor-docs/3.0/docs/getting-started/controllers.md

Controllers

Controllers are a great way to organize your code. They are collections of methods that accept a request and return a response.

A good place to put your controllers is in the Controllers folder.

Methods

Let's take a look at an example controller.

import Vapor

final class HelloController {
	func greet(_ req: Request) throws -> String {
		return "Hello!"
	}
}

Controller methods should always accept a Request and return something ResponseRepresentable. This also includes futures whose expectations are ResponseRepresentable (i.e, Future<String>).

To use this controller, we can simply initialize it, then pass the method to a router.

let helloController = HelloController()
router.get("greet", use: helloController.greet)

Use Services

You will probably want to access your application's services from within your controllers. Luckily this is easy to do. First, declare what services your controller needs in its init method. Then store them as properties on the controller.

final class HelloController {
	let hasher: BCryptHasher

	init(hasher: BCryptHasher) {
		self.hasher = hasher
	}

	...
}

Next, use the application to create these services when you initialize your controller.

let helloController = try HelloController(
	hasher: app.make()
)