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JSON API Endpoint

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When we click the heart icon, we need to send an AJAX request to the server that will, eventually, update something in a database to show that the we liked this article. That API endpoint also needs to return the new number of hearts to show on the page... ya know... in case 10 other people liked it since we opened the page.

In ArticleController, make a new public function toggleArticleHeart():

... lines 1 - 9
class ArticleController extends AbstractController
{
... lines 12 - 39
public function toggleArticleHeart($slug)
{
... lines 42 - 44
}
}

Then add the route above: @Route("/news/{slug}") - to match the show URL - then /heart. Give it a name immediately: article_toggle_heart:

... lines 1 - 9
class ArticleController extends AbstractController
{
... lines 12 - 36
/**
* @Route("/news/{slug}/heart", name="article_toggle_heart")
*/
public function toggleArticleHeart($slug)
{
... lines 42 - 44
}
}

I included the {slug} wildcard in the route so that we know which article is being liked. We could also use an {id} wildcard once we have a database.

Add the corresponding $slug argument. But since we don't have a database yet, I'll add a TODO: "actually heart/unheart the article!":

... lines 1 - 9
class ArticleController extends AbstractController
{
... lines 12 - 36
/**
* @Route("/news/{slug}/heart", name="article_toggle_heart")
*/
public function toggleArticleHeart($slug)
{
// TODO - actually heart/unheart the article!
... lines 43 - 44
}
}

Returning JSON

We want this API endpoint to return JSON... and remember: the only rule for a Symfony controller is that it must return a Symfony Response object. So we could literally say return new Response(json_encode(['hearts' => 5])).

But that's too much work! Instead say return new JsonResponse(['hearts' => rand(5, 100)]:

... lines 1 - 6
use Symfony\Component\HttpFoundation\JsonResponse;
... lines 8 - 9
class ArticleController extends AbstractController
{
... lines 12 - 36
/**
* @Route("/news/{slug}/heart", name="article_toggle_heart")
*/
public function toggleArticleHeart($slug)
{
// TODO - actually heart/unheart the article!
return new JsonResponse(['hearts' => rand(5, 100)]);
}
}

Tip

Or use the controller shortcut!

return $this->json(['hearts' => rand(5, 100)]);

Note that since PHP 7.0 instead of rand() you may want to use random_int() that generates cryptographically secure pseudo-random integers. It's more preferable to use unless you hit performance issue, but with just several calls it's not even noticeable.

There's nothing special here: JsonResponse is a sub-class of Response. It calls json_encode() for you, and also sets the Content-Type header to application/json, which helps your JavaScript understand things.

Let's try this in the browser first. Go back and add /heart to the URL. Yes! Our first API endpoint!

Tip

My JSON looks pretty thanks to the JSONView extension for Chrome!

Making the Route POST-Only

Eventually, this endpoint will modify something on the server - it will "like" the article. So as a best-practice, we should not be able to make a GET request to it. Let's make this route only match when a POST request is made. How? Add another option to the route: methods={"POST"}:

... lines 1 - 9
class ArticleController extends AbstractController
{
... lines 12 - 36
/**
* @Route("/news/{slug}/heart", name="article_toggle_heart", methods={"POST"})
*/
public function toggleArticleHeart($slug)
{
... lines 42 - 44
}
}

As soon as we do that, we can no longer make a GET request in the browser: it does not match the route anymore! Run:

./bin/console debug:router

And you'll see that the new route only responds to POST requests. Pretty cool. By the way, Symfony has a lot more tools for creating API endpoints - this is just the beginning. In future tutorials, we'll go further!

Hooking up the JavaScript & API

Our API endpoint is ready! Copy the route name and go back to article_show.js. But wait... if we want to make an AJAX request to the new route... how can we generate the URL? This is a pure JS file... so we can't use the Twig path() function!

Actually, there is a really cool bundle called FOSJsRoutingBundle that does allow you to generate routes in JavaScript. But, I'm going to show you another, simple way.

Back in the template, find the heart section. Let's just... fill in the href on the link! Add path(), paste the route name, and pass the slug wildcard set to a slug variable:

... lines 1 - 4
{% block body %}
<div class="container">
<div class="row">
<div class="col-sm-12">
<div class="show-article-container p-3 mt-4">
<div class="row">
<div class="col-sm-12">
... line 13
<div class="show-article-title-container d-inline-block pl-3 align-middle">
... lines 15 - 18
<span class="pl-2 article-details">
... line 20
<a href="{{ path('article_toggle_heart', {slug: slug}) }}" class="fa fa-heart-o like-article js-like-article"></a>
</span>
</div>
</div>
</div>
... lines 26 - 97
</div>
</div>
</div>
</div>
{% endblock %}
... lines 104 - 109

Actually... there is not a slug variable in this template yet. If you look at ArticleController, we're only passing two variables. Add a third: slug set to $slug:

... lines 1 - 9
class ArticleController extends AbstractController
{
... lines 12 - 22
public function show($slug)
{
... lines 25 - 30
return $this->render('article/show.html.twig', [
... line 32
'slug' => $slug,
... line 34
]);
}
... lines 37 - 46
}

That should at least set the URL on the link. Go back to the show page in your browser and refresh. Yep! The heart link is hooked up.

Why did we do this? Because now we can get that URL really easily in JavaScript. Add $.ajax({}) and pass method: 'POST' and url set to $link.attr('href'):

$(document).ready(function() {
$('.js-like-article').on('click', function(e) {
... lines 3 - 5
$link.toggleClass('fa-heart-o').toggleClass('fa-heart');
$.ajax({
method: 'POST',
url: $link.attr('href')
... lines 11 - 12
})
});
});

That's it! At the end, add .done() with a callback that has a data argument:

$(document).ready(function() {
$('.js-like-article').on('click', function(e) {
... lines 3 - 7
$.ajax({
method: 'POST',
url: $link.attr('href')
}).done(function(data) {
... line 12
})
});
});

The data will be whatever our API endpoint sends back. That means that we can move the article count HTML line into this, and set it to data.hearts:

$(document).ready(function() {
$('.js-like-article').on('click', function(e) {
... lines 3 - 7
$.ajax({
... lines 9 - 10
}).done(function(data) {
$('.js-like-article-count').html(data.hearts);
})
});
});

Oh, and if you're not familiar with the .done() function or Promises, I'd highly recommend checking out our JavaScript Track. It's not beginner stuff: it's meant to take your JS up to the next level.

Anyways... let's try it already! Refresh! And... click! It works!

And... I have a surprise! See this little arrow icon in the web debug toolbar? This showed up as soon as we made the first AJAX request. Actually, every time we make an AJAX request, it's added to the top of this list! That's awesome because - remember the profiler? - you can click to view the profiler for any AJAX request. Yep, you now have all the performance and debugging tools at your fingertips... even for AJAX calls.

Oh, and if there were an error, you would see it in all its beautiful, styled glory on the Exception tab. Being able to load the profiler for an AJAX call is kind of an easter egg: not everyone knows about it. But you should.

I think it's time to talk about the most important part of Symfony: Fabien. I mean, services.

Leave a comment!

What PHP libraries does this tutorial use?

// composer.json
{
    "require": {
        "php": "^7.1.3",
        "ext-iconv": "*",
        "sensio/framework-extra-bundle": "^5.1", // v5.1.3
        "symfony/asset": "^4.0", // v4.0.3
        "symfony/console": "^4.0", // v4.0.14
        "symfony/flex": "^1.0", // v1.2.7
        "symfony/framework-bundle": "^4.0", // v4.0.14
        "symfony/lts": "^4@dev", // dev-master
        "symfony/twig-bundle": "^4.0", // v4.0.3
        "symfony/web-server-bundle": "^4.0", // v4.0.3
        "symfony/yaml": "^4.0" // v4.0.14
    },
    "require-dev": {
        "easycorp/easy-log-handler": "^1.0.2", // v1.0.4
        "sensiolabs/security-checker": "^5.0", // v5.0.3
        "symfony/debug-bundle": "^3.3|^4.0", // v4.0.3
        "symfony/dotenv": "^4.0", // v4.0.14
        "symfony/monolog-bundle": "^3.0", // v3.1.2
        "symfony/phpunit-bridge": "^3.3|^4.0", // v4.0.3
        "symfony/profiler-pack": "^1.0", // v1.0.3
        "symfony/var-dumper": "^3.3|^4.0" // v4.0.3
    }
}