Adam Cameron's Dev Blog: Part 7: Using Symfony

G'day:

Familiar boilterplate about how this is one in a series follows. Please note that I initially intended this to be a single article, but by the time I had finished the first two sections, it was way too long for a single read, so I've split it into the following sections, each as their own article:

As indicated: this is the seventh article in the series, and follows on from Part 6: Installing Symfony. It's probably best to go have a breeze through the earlier articles first, in particular the immediately preceding one. Also as indicated in earlier articles: I'm a noob with all this stuff so this is basically a log of me working out how to get things working, rather than any sort of informed tutorial on the subject. Also I was only originally "planning" one article on getting the Symfony stuff sorted out, but yesterday's exercise was more involved that I'd've liked, so I stopped once I had Symfony serving up its welcome page, and today focusing on the config / code of getting a route, controller, model, view (actually there's no model or view in this endpoint; it's all just done in the controller) up and running.

Two caveats before I start.

Firstly: this is the first time I've done anything with Symfony other than reviewing the work of other members of my team - the ones doing the actual work. I have some familiarity with Symfony, but it's very very superficial.

Secondly, I will also be up front that I don't like Symfony's approach to MVC frameworking. Symfony is kind of a "lifestyle choice": it's opinionated, it expects you to do things a certain way, and it puts its nose into everything. This is opposed to something like Silex which simply provides the bare bones wiring to handle the ubiquitous web application requirement of guiding processing through routing, controller, model and view; other than that it just gets out of the way and is pretty invisible. I loved Silex, but sadly it's EOL so I need to move on. And, yeah, I'm being curmudgeonly and pre-judgemental as I go, I know. I do know Symfony is immensely popular, and I also know from my exposure to using its various independent libraries that it's been developed in a thoughtful, thorough manner. I expect I'm largely just being change-averse here. However I'm forewarning you now, as this will no-doubt come across in my tone, and my patience when things don't go exactly how I'd like them too (like some sort of spoilt brat). But if you've read this blog before… you probably already expect this.

Now that I have that out of my system (maybe), what's my aim for today? When I started yesterday, the intent of my work was described in this functional test:

/** @coversNothing */
public function testGreetingsEndPointReturnsPersonalisedGreeting()
{
    $testName = 'Zachary';
     $expectedGreeting = (object) [
        'name' => $testName,
        'greeting' => "G'day $testName"
    ];

    $client = new Client([
        'base_uri' => 'http://webserver.backend/'
    ]);

    $response = $client->get(
        "greetings/$testName/",
        ['http_errors' => false]
    );
    $this->assertEquals(Response::HTTP_OK, $response->getStatusCode());

    $contentTypes = $response->getHeader('Content-Type');
    $this->assertCount(1, $contentTypes);
    $this->assertSame('application/json', $contentTypes[0]);

    $responseBody = $response->getBody();
    $responseObject = json_decode($responseBody);
    $this->assertEquals($expectedGreeting, $responseObject);
}

In humanspeke, what I'm gonna do is:

create a route /greetings/[some name here]/;
return an object as JSON;
that confirms the name sent, plus has a greeting string for that name.

Very "Hello World". I did indicate I was not gonna be pushing the boat out too much here.

To start let's run that test, and watch it fail with a 404…

root@5565d6f15aca:/usr/share/fullstackExercise# vendor/bin/phpunit
PHPUnit 9.5.0 by Sebastian Bergmann and contributors.

.F.... 6 / 6 (100%)

Time: 00:04.414, Memory: 14.00 MB

There was 1 failure:

1) adamCameron\fullStackExercise\tests\functional\SymfonyTest::testGreetingsEndPointReturnsPersonalisedGreeting
Failed asserting that 404 matches expected 200.

/usr/share/fullstackExercise/tests/functional/SymfonyTest.php:63

FAILURES!
Tests: 6, Assertions: 12, Failures: 1.

Generating code coverage report in HTML format ... done [00:01.162]
root@5565d6f15aca:/usr/share/fullstackExercise#

That one failure is the one we want to see, so that's good: I have a test failing in exactly they way I expect it to be, so now I need to work out how to add a route and all that sort of jazz. Time to RTFM. Back soon.

…

Right so the docs for Symfony have been incredibly helpful so far. That's not sarcasm: they've been really bloody good! I'd been looking at the Installing & Setting up the Symfony Framework page, and one of its last links is to Create your First Page in Symfony. This steps one through setting up a route and the controller that services it. The first example did not have a "runtime" parameter in the URL slug like I need here, but that was covered in another linked-to page Routing (specifically the Route Parameters section of same). That was all the information I seemed to need for my code, so off I went.

Routing is done in config/routes.yaml, and there's an example in there already. So it was easy to stick my new route in:

#index:
#    path: /
#    controller: App\Controller\DefaultController::index

greetings:
  path: /greetings/{name}
  controller: adamCameron\fullStackExercise\Controller\GreetingsController::doGet

Curly braces around the {name} just mean that that part of the URL slug is dynamic, and its value is passed to the controller method. I could (and should!) put validation on this, but that's getting ahead of myself. The current requirement I have set only handles the happy path, so we'll stick to that.

The controller goes in the src/Controller directory. I'm more accustomed to using headlessCamelCase for my namespace parts, but I'll stick with Symfony's precedent here:

namespace adamCameron\fullStackExercise\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Response;

class GreetingsController extends AbstractController
{
    public function doGet(string $name) : Response
    {
        $greetingsResponse = [
            'name' => $name,
            'greeting' => "G'day $name"
        ];

        return new JsonResponse($greetingsResponse);
    }
}

This shows how the dynamic part of the slug from the route passes through into the controller method. Cool. From there I've gone my own way from the docs there cos Silex uses Symfony's request/response mechanism, so I know I can just return a JsonResponse like that, and it'll handle the 200-OK and the application/json part of the requirement. The docs integrate using Twig here to render some output, but there's no need for that complexity here. I suppose here the creation of $greetingsResponse is my "model", and the decision to just return a JsonResponse is my "view".

Being quite pleased with myself at how simple that was, I ran my test to verify how clever I was:

root@3fc72bf44d38:/usr/share/fullstackExercise# vendor/bin/phpunit tests/functional/SymfonyTest.php --filter=testGreetingsEndPointReturnsPersonalisedGreeting
PHPUnit 9.5.0 by Sebastian Bergmann and contributors.

F 1 / 1 (100%)

Time: 00:02.607, Memory: 8.00 MB

There was 1 failure:

1) adamCameron\fullStackExercise\tests\functional\SymfonyTest::testGreetingsEndPointReturnsPersonalisedGreeting
Failed asserting that 500 matches expected 200.

/usr/share/fullstackExercise/tests/functional/SymfonyTest.php:63

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.

Generating code coverage report in HTML format ... done [00:01.790]
root@3fc72bf44d38:/usr/share/fullstackExercise#

rrarr! OK, not so clever after all it seems. Hitting the URL in the browser gives me more information:

What is this thing on about? See where it's looking for my controller? It's looking for a class App\Controller\GreetingsController, but that class is not in App/Controller, it's in adamCameron/fullStackExercise/Controller, and that's where the route code says it is. I have re-checked everything, and it's all legit.

Sigh. I could guess what it is. Symfony being a) "clever", and b) "opinionated". If you've just read the previous article, you might recall me raising my eyebrow at this bit in composer.json:

"autoload": {
    "psr-4": {
        "App\\": "src/",
        "adamCameron\\fullStackExercise\\": "src/"
    }
},

At the time I was just observing what a dumb namespace that was, but I'm now guessing that in Symfony's opinion that is the namespace we all should be using. I remembered something about some other autowiring config that Symfony has, and guessed there was something in there that might cater to classes in the App namespace, but not other namespaces. Even if the namespaces are explicit in the code (as they are here). I located the culprit in config/services.yaml:

services:
    # default configuration for services in *this* file
    _defaults:
        autowire: true      # Automatically injects dependencies in your services.
        autoconfigure: true # Automatically registers your services as commands, event subscribers, etc.

    # makes classes in src/ available to be used as services
    # this creates a service per class whose id is the fully-qualified class name
    App\:
        resource: '../src/'
        exclude:
            - '../src/DependencyInjection/'
            - '../src/Entity/'
            - '../src/Kernel.php'
            - '../src/Tests/'

    # controllers are imported separately to make sure services can be injected
    # as action arguments even if you don't extend any base controller class
    App\Controller\:
        resource: '../src/Controller/'
        tags: ['controller.service_arguments']

    # add more service definitions when explicit configuration is needed
    # please note that last definitions always *replace* previous ones

So there's magic taking place for App; I guess I need to make it magical for my actual namespace instead. I'm never gonna write code with App as its namespace, so I'm just gonna punt that I can change that to adamCameron\fullStackExercise\: and adamCameron\fullStackExercise\Controller\: and it'll all be fine. I think ATM I only need to monkey with the Controller one, but I might as well do both now I guess. So with that change in place, I re-run the test:

All right, that was easily located / solved and is not the end of the world. However this from Symfony's error message irks me: "The file was found but the class was not in it, the class name or namespace probably has a typo". No mate. That's not the problem at all. The problem is that despite me giving you the exact fully-qualified namespaced class name in the route config, and the namespace in the class file was correct, and in the right place in the file system… and if you just left things be then you would have found the correct class. But: no. You had to try to be clever, and you failed miserably. I really frickin' hate it when technology goes "nono [patronising grimace] I've got this, I'll do it for you" (I know some devs like this too…), and it gets it wrong. I'm all for Symfony having the helpers there should one want them, but it shouldn't make these assumptions. I guess had it gone "hey aaah… that namespace yer using for yer controller? Ya need to configure that to work mate. Go have a look in config.yaml", then I'd just be going "yeah nice one: thanks for that". But then again most people would probably not have written this ranty paragraph at all, and just moved on with their lives, eh? Hey at least I'm self-aware.

All in all, even with the config/namespace hiccup, getting a simple route working was pretty bloody easy here. And this is a good thing about Symfony.

That was actually pretty short. It was about 500 words and some test-runs longer, as I had encountered a weird issue which I was moaning about. However when doing a final read-through of this before pressing "send", I looked at it some more, and it turns out it was just me being a div, and the problem was firmly of the PEBCAK variety. So… erm… I decided to delete that bit. Ahem.

Next I have to start doing some front-end-ish stuff so I've got an excuse to try out Vue.js. This should be interesting. I've never even looked @ Vue.js before. I bet I'll disagree with some of its opinions eh? Stay tuned…

Righto.

--
Adam

Thursday 14 January 2021

Part 7: Using Symfony