Tutorial: How to write Controllers
At the end of this article you’ll know how to implement and use controllers 🙌🏻
You can find the result of this tutorial on github here
This tutorial is a natural follow-up of How to write Models using Fluent. You can either go for that tutorial first and come back later or be a rebel, skip it and read on 😊
Index
1. Create a new project
2. Generate Xcode project
3. Why we need controllers
4. Create your first controller
5. Where to go from here
1. Create a new project
We will use the outcome of the aforementioned tutorial as a template to create our new project:
vapor new projectName --template=vaporberlin/my-first-model2. Generate Xcode project
Before we generate an Xcode project we would have to change the package name within Package.swift:
// swift-tools-version:4.0
import PackageDescriptionlet package = Package(
name: "projectName", // changed
dependencies: [
// 💧 A server-side Swift web framework.
.package(url: "https://github.com/vapor/vapor.git", from: "3.0.0"),
.package(url: "https://github.com/vapor/leaf.git", from: "3.0.0-rc"),
.package(url: "https://github.com/vapor/fluent-sqlite.git", from: "3.0.0-rc")
],
targets: [
.target(name: "App", dependencies: ["Vapor", "Leaf", "FluentSQLite"]),
.target(name: "Run", dependencies: ["App"]),
.testTarget(name: "AppTests", dependencies: ["App"]),
]
)
Now in the terminal at the root directory projectName/ execute:
vapor update -yIt may take a bit fetching the dependency, but when done you should have a project structure like this:
projectName/
├── Package.swift
├── Sources/
│ ├── App/
│ │ ├── Models/
│ │ │ └── User.swift
│ │ ├── app.swift
│ │ ├── boot.swift
│ │ ├── configure.swift
│ │ └── routes.swift
│ └── Run/
│ └── main.swift
├── Tests/
├── Public/
├── Dependencies/
└── Products/In case you see an error with “CNIOOpenSSL” when running — you’re missing a dependency. Just run brew upgrade vapor and re-generate the project ✌🏻😊
3. Why we need controllers
If we look into routes.swift we should see two functions (routes) from which the first would return a view with a list of users and the second would create a new user. Imagine you would now want to implement the possibility to create short text snippets and also list them. You would probably have a route similar to get(“snippet”) to get all snippets as a list and maybe a post(“snippet”) to create new snippets. If you would do that in routes.swift it would be kind of fine as long as your project is super small having only about 4–6 routes. As soon as your project gets bigger the routes.swift file would get bigger too and you’ll start loosing overview. Also having one file taking care of multiple responsibilities is not considered good practice 🤓. At the end a user is something different than a snippet 😊. Controllers to the rescue!
4. Create your first controller
What we want to do now is to put everything user related into an own controller. So go ahead and create the following directory and file:
projectName/
├── Package.swift
├── Sources/
│ ├── App/
│ │ ├── Controllers/ // added
│ │ │ └── UserController.swift // added
│ │ ├── Models/
│ │ ├── app.swift
│ │ ├── boot.swift
│ │ ├── configure.swift
│ │ └── routes.swift
│ └── Run/
│ └── main.swift
├── Tests/
├── Public/
├── Dependencies/
└── Products/I used the terminal. In projectName/ execute
> mkdir Sources/App/Controllers/
> touch Sources/App/Controllers/UserController.swift
You may have to re-generate your Xcode project with vapor xcode -y in order to let Xcode see your new directory.
So let’s move our get(“user”) functionality into our Controller by writing the following code into UserController.swift:
import Vaporfinal class UserController { func list(_ req: Request) throws -> Future<View> {
return User.query(on: req).all().flatMap { users in
let data = ["userlist": users]
return try req.view().render("userview", data)
}
}
}
Let me for short explain. We are defining a new function calling it whatever we want, it makes sense to call it list since we are in a user controller and want this function to return a list of users. Functions that are meant to handle request always look like this:
func myFunc(_ req: Request) throws -> Future<Something> {
...
}Notice the Future<Something> as a return value. That Something depends on what you want to return. For example if you want to return a View just as we did you would write Future<View> as a return value. But if you want to return let’s say a list of users as JSON you would write Future<[User]>. And within your function you would just do: return User.query(on: req).all().
Moving on! How do we link a route like get(“user”) in our routes.swift to use our list function? It is so super simple, in your routes.swift write:
import Vaporpublic func routes(_ router: Router) throws { let userController = UserController() // added
router.get("users", use: userController.list) // added router.post("users") { req -> Future<Response> in
...
}
}
We deleted the former route get(“user”) and the import Leaf here
We initiate our user controller and define that get(“user”) shall use our user controllers list function.
If you now cmd+r or run and fire up the /users route it will just work!
For completeness sake let’s move post(“users”) to our controller too 😊
In our UserController.swift:
import Vaporfinal class UserController { func list(_ req: Request) throws -> Future<View> {
...
} func create(_ req: Request) throws -> Future<Response> {
return try req.content.decode(User.self).flatMap { user in
return user.save(on: req).map { _ in
return req.redirect(to: "users")
}
}
}
}
And then finally in our routes.swift:
import Vaporpublic func routes(_ router: Router) throws { let userController = UserController()
router.get("users", use: userController.list)
router.post("users", use: userController.create) // added
}
And that’s it! You successfully implemented your first controller 🎉 ! Whoop!
5. Where to go from here
You can find a list of all tutorials with example projects on Github here:
👉🏻 https://github.com/vaporberlin/vaporschool
