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Controllers

Controllers help you organize related functionality into a single place. They can also be used to create RESTful resources.

Basic

A basic controller looks like the following:

import Vapor
import HTTP

final class HelloController {
    func sayHello(_ req: Request) throws -> ResponseRepresentable {
        guard let name = req.data["name"]?.string else { 
            throw Abort(.badRequest)
        }

        return "Hello, \(name)"
    }
}

Simple controllers don't need to conform to any protocols. You are free to design them however you see fit.

Registering

The only required structure is the signature of each method in the controller. In order to register this method into the router, it must have a signature like (Request) throws -> ResponseRepresentable. Request and ResponseRepresentable are made available by importing the HTTP module.

import Vapor
let drop = try Droplet()

let hc = HelloController()
drop.get("hello", handler: hc.sayHello)

Since the signature of our sayHello method matches the signature of the closure for the drop.get method, we can pass it directly.

Type Safe

You can also use controller methods with type-safe routing.

final class HelloController {
    ...

    func sayHelloAlternate(_ req: Request) -> ResponseRepresentable {
        let name: String = try req.parameters.next(String.self)
        return "Hello, \(name)"
    }
}

We add a new method called sayHelloAlternate to the HelloController that fetches a String from the request's parameters.

let hc = HelloController()
drop.get("hello", String.parameter, handler: hc.sayHelloAlternate)

Since drop.get accepts a signature (Request) throws -> ResponseRepresentable, our method can now be used as the closure for this route.

Note

Read more about type safe routing in the Routing Parameters section.

Resources

Controllers that conform to ResourceRepresentable can be easily registered into a router as a RESTful resource. Let's look at an example of a UserController.

final class UserController {
    func index(_ req: Request) throws -> ResponseRepresentable {
        return try User.all().makeJSON()
    }

    func show(_ req: Request) throws -> ResponseRepresentable {
        let user = try req.parameters.next(User.self)
        return user
    }
}

Here is a typical user controller with an index and show route. Indexing returns a JSON list of all users and showing returns a JSON representation of a single user.

We could register the controller like so:

let users = UserController()
drop.get("users", handler: users.index)
drop.get("users", User.self, handler: users.show)

But ResourceRepresentable makes this standard RESTful structure easy.

extension UserController: ResourceRepresentable {
    func makeResource() -> Resource<User> {
        return Resource(
            index: index,
            show: show
        )
    }
}

Conforming UserController to ResourceRepresentable requires that the signatures of the index and show methods match what the Resource<User> is expecting.

Now that UserController conforms to ResourceRepresentable, registering the routes is easy.

let users = UserController()
drop.resource("users", users)

drop.resource will take care of registering only the routes that have been supplied by the call to makeResource(). In this case, only the index and show routes will be supplied.

Actions

Below is a table describing all of the actions available.

Action Method Path Note
index GET /users Returns all users, optionally filtered by the request data.
store POST /users Creates a new user from the request data.
show GET /users/:id Returns the user with the ID supplied in the path.
replace PUT /users/:id Updates the specified user, setting any fields not present in the request data to nil.
update PATCH /users/:id Updates the specified user, only modifying fields present in the request data.
destroy DELETE /users/:id Deletes the specified user.
clear DELETE /users Deletes all users, optionally filtered by the request data.
create GET /users/create Displays a form for creating a new user.
edit GET /users/:id/edit Displays a form for editing the specified user.
aboutItem OPTIONS /users/:id Meta action. Displays information about which actions are supported.
aboutMultiple OPTIONS /users Meta action. Displays information about which actions are supported.

Note

The aboutItem and aboutMultiple meta actions are implemented automatically if not overridden.

Tip

The difference between replace and update is subtle but important: If a field does not exist in the request data (for example, the user's age is missing), update should simply not update that field where as replace should set it to nil. If required data is missing from a replace request, an error should be thrown.

Folder

Controllers can go anywhere in your application, but they are most often stored in the App/Controllers/ directory.

Tip

If you are building a large application, you may want to create your controllers in a separate module. This will allow you to perform unit tests on your controllers.