Controllers
foal generate controller my-controller
import { Context, Get, HttpResponseOK } from '@foal/core';
export class MyController {
@Get('/flights')
listFlights(ctx: Context) {
return new HttpResponseOK([]);
}
}
Description
Controllers are the front door of your application. They intercept all incoming requests and return the responses to the client.
The code of a controller should be concise. If necessary, controllers can delegate some tasks to services (usually the business logic).
Controller Architecture
A controller is simply a class of which some methods are responsible for a route. These methods must be decorated by one of theses decorators Get
, Post
, Patch
, Put
, Delete
, Head
or Options
. They may be asynchronous.
Example:
import { Get, HttpResponseOK, Post } from '@foal/core';
class MyController {
@Get('/foo')
foo() {
return new HttpResponseOK('I\'m listening to GET /foo requests.');
}
@Post('/bar')
bar() {
return new HttpResponseOK('I\'m listening to POST /bar requests.');
}
}
Controllers may have sub-controllers declared in the subControllers
property.
Example:
import { Get, HttpResponseOK, Post } from '@foal/core';
class MySubController {
@Get('/foo')
foo() {
return new HttpResponseOK('I\'m listening to GET /barfoo/foo requests.');
}
}
class MyController {
subControllers = [
controller('/barfoo', MySubController)
]
@Post('/bar')
bar() {
return new HttpResponseOK('I\'m listening to POST /bar requests.');
}
}
The AppController
The AppController
is the main controller of your application. It is directly bound to the request handler. Every controller must be, directly or indirectly, a sub-controller of the AppController
.
Example:
import { controller } from '@foal/core';
import { ApiController } from './controllers/api.controller';
export class AppController {
subControllers = [
controller('/api', ApiController)
];
}
Contexts & HTTP Requests
The Context
object
On every request, the controller method is called with a Context
object. This context is unique and specific to the request.
It has four properties:
- a
request
(type:Request
) giving information about the HTTP request received, - a
state
(type:object
) which can be used to share data between hooks (see Hooks), - a
user
(type:any
orundefined
) giving information on the current user (see Authentication), - and a
session
(type:Session
orundefined
) containing the session data if you use sessions.
HTTP Requests
The request
property is an ExpressJS request object. Its complete documentation can be consulted here. The below sections detail common use cases.
Read the Body
The request body is accessible with the body
attribute. Form data and JSON objects are automatically converted to JavaScript objects in FoalTS.
POST /products
{
"name": "milk"
}
import { Context, HttpResponseCreated, Post } from '@foal/core';
class AppController {
@Post('/products')
createProduct(ctx: Context) {
const body = ctx.request.body;
// Do something.
return new HttpResponseCreated();
}
}
Read Path Parameters
Path parameters are accessible with the params
attribute.
GET /products/3
import { Context, HttpResponseOK, Post } from '@foal/core';
class AppController {
@Get('/products/:id')
readProduct(ctx: Context) {
const productId = ctx.request.params.id;
// Do something.
return new HttpResponseOK(/* something */);
}
}
Read Query Parameters
Query parameters are accessible with the query
attribute.
GET /products?limit=3
import { Context, HttpResponseOK, Post } from '@foal/core';
class AppController {
@Get('/products')
readProducts(ctx: Context) {
const limit = ctx.request.query.limit;
// Do something.
return new HttpResponseOK(/* something */);
}
}
Read Headers
Headers are accessible with the get
method.
import { Context, Get } from '@foal/core';
class AppController {
@Get('/')
index(ctx: Context) {
const token: string|undefined = ctx.request.get('Authorization');
// ...
}
}
Read Cookies
Cookies are accessible with the cookies
attribute.
import { Context, Get } from '@foal/core';
class AppController {
@Get('/')
index(ctx: Context) {
const sessionID: string|undefined = ctx.request.cookies.sessionID;
// ...
}
}
The Controller Method Arguments
Available in Foal v1.9.0 onwards.
The path paramaters and request body are also passed as second and third arguments to the controller method.
import { Context, HttpResponseCreated, Put } from '@foal/core';
class AppController {
@Put('/products/:id')
updateProduct(ctx: Context, { id }, body) {
// Do something.
return new HttpResponseCreated();
}
}
HTTP Responses
HTTP responses are defined using HttpResponse
objects. Each controller method must return an instance of this class (or a promise of this instance).
Here are subclasses that you can use:
HTTP method | Response class | Is abstract? |
---|---|---|
2XX Success | ||
2XX | HttpResponseSuccess | yes |
200 | HttpResponseOK | no |
201 | HttpResponseCreated | no |
3XX Redirection | ||
3XX | HttpResponseRedirection | yes |
301 | HttpResponseMovedPermanently | no |
302 | HttpResponseRedirect | no |
4XX Client errors | ||
4XX | HttpResponseClientError | yes |
400 | HttpResponseBadRequest | no |
401 | HttpResponseUnauthorized | no |
403 | HttpResponseForbidden | no |
404 | HttpResponseNotFound | no |
405 | HttpResponseMethodNotAllowed | no |
409 | HttpResponseConflict | no |
5XX Server errors | ||
5XX | HttpResponseServerError | yes |
500 | HttpResponseInternalServerError | no |
501 | HttpResponseNotImplemented | no |
Most of these responses accept a body
at instantiation. It can be a Buffer
object, a string, an object, a number, an array, or even a Node.JS stream.
Example with a body
new HttpResponseBadRequest({
message: 'The foo field is missing.'
})
In case the body parameter is a stream, you must specify it using the stream
option.
Example with a Node.JS stream as body
new HttpResponseOK(myStream, { stream: true })
Adding Headers
Example
import { Get, HttpResponseOK } from '@foal/core';
class AppController {
@Get('/')
index() {
return new HttpResponseOK()
.setHeader('Cache-Control', 'max-age=604800, public');
}
}
Adding cookies
Example with no cookie directives
import { Get, HttpResponseOK } from '@foal/core';
class AppController {
@Get('/')
index() {
return new HttpResponseOK()
.setCookie('state', 'foobar');
}
}
Example with cookie directives
import { Get, HttpResponseOK } from '@foal/core';
class AppController {
@Get('/')
index() {
return new HttpResponseOK()
.setCookie('sessionID', 'xxxx', {
domain: 'example.com',
// expires: new Date(2020, 12, 12),
httpOnly: true,
maxAge: 3600,
path: '/',
secure: true,
sameSite: 'lax',
});
}
}
The
maxAge
cookie directive defines the number of seconds until the cookie expires.
Testing Controllers
A controller is a simple class and so can be tested as is. Note that hooks are ignored upon testing.
api.controller.ts (example)
class ApiController {
@Get('/users/me')
@JWTRequired()
getCurrentUser(ctx: Context) {
return new HttpResponseOK(ctx.user):
}
}
api.controller.spec.ts (example)
import { strictEqual } from 'assert';
import { Context, createController, HttpResponseOK, isHttpResponseOK } from '@foal/core';
import { ApiController } from './api.controller';
describe('ApiController', () => {
it('should return the current user.', () => {
// Instantiate the controller.
const controller = createController(ApiController);
// Create a fake user (the current user)
const user = { name: 'Alix' };
// Create a fake Context object to simulate the request.
const ctx = new Context({}); // "{}" is the request body.
ctx.user = user;
// Execute the controller method and save the response.
const response = controller.getCurrentUser(ctx);
if (!isHttpResponseOK(response)) {
throw new Error('The response should be an HttpResponseOK');
}
strictEqual(response.body, user);
});
});
Due to the way packages are managed by npm, you should always use
isHttpResponseOK(response)
rather thanresponse instanceof HttpResponseOK
to avoid reference bugs.
Inheriting Controllers
Example:
abstract class ParentController {
@Get('/foo')
foo() {
return new HttpResponseOK();
}
}
class ChildController extends ParentController {
@Post('/bar')
bar() {
return new HttpResponseOK();
}
}
You can also override foo
. If you don't add a Get
, Post
, Patch
, Put
, Delete
, Head
or Options
decorator then the parent path and HTTP method are used. If you don't add a hook, then the parent hooks are used. Otherwise they are all discarded.