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Controllers

Controllers are attached to routes and are the common point of interaction between your models and views.

In typical web applications, you will begin by binding a controller method to a route, make use of models to fetch data and send that data to the view to render HTML.

How Controllers Work?

  • Controllers are defined inside app/Http/Controllers directory. To keep your code maintainable, you are free to create nested directories inside the Controllers directory.

  • Make use of make:controller command to create a new controller.

    ./ace make:controller Home
# or
./ace make:controller User --resource

# create: app/Http/Controllers/HomeController.js

    --resource flag will create a controller with predefined resourceful methods.

  • Controllers are defined as ES2015 classes, which makes it easier to test them since you can inject runtime dependencies to the constructor and mock them(if required) during tests.

  • Controllers methods are referenced as a String to the routes.

    Route.get('users', 'UsersController.index')

    The first part before the dot(.) is a reference to the controller file that is UserController and the second part is the controller method.

Basic Example

Let’s take a basic example of rendering all the users using the route, controller, model, and view.

Route
Route.get('users', 'UsersController.index')
Controller
const User = use('App/Model/User')

class UsersController {

  * index (request, response) {
    const users = yield User.all()
    yield response.sendView('users', { users: users.toJSON() })
  }

}
View
{% for user in users %}
  <h2>{{ user.username }}</h2>
{% endfor %}

Dependency Injection

Since controllers are ES2015 classes, you can easily inject dependencies to the constructor, instead of manually requiring them. The benefit of injecting dependencies is that you can mock them at the time of testing.

Mocking dependencies is very subjective and is not always required. Still, AdonisJs does not limit you if you want to mock dependencies.

Defining Controller

class UsersController {

  static get inject () {
    return ['App/Model/User'] (1)
  }

  constructor (User) { (2)
    this.User = User
  }

  * index () {
    const users = yield this.User.all()
  }

}
1 Getter inject returns an array of namespaces to be injected to the constructor. They are passed in the order they are defined.
2 Class constructor will receive the injections as parameters.

Writing Test

Below test example is written to give you an idea on how to mock dependencies and may not be the best way of writing tests. 
const UsersController = use('App/Http/Controllers/User')

class FakeUser {
  static * all () {
    return {} // dummy users
  }
}

const user = new UsersController(FakeUser)