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Sluggable & other Wonderful Behaviors

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We're using Faker to generate a random slug for each dummy article. Thanks to this, back on the homepage, look at the URLs: they're truly random slugs: they have no relation to the title.

But, really, shouldn't the slug be generated from the title? What I mean is, if I set the Article's title, something should automatically convert that into a slug and make sure it's unique in the database. We shouldn't need to worry about doing that manually.

And... yea! There's a really cool library that can do this, and a bunch of other magic! Google for StofDoctrineExtensionsBundle, and then click into its documentation.

Ok, let me explain something: there is a normal, PHP library called DoctrineExtension, which can add a lot of different behaviors to your entities, like sluggable, where you automatically generate the slug from another field. Other behaviors include Loggable, where each change to an entity is tracked, or Blameable, where the user who created or updated an entity is automatically recorded.

Installing StofDoctrineExtensionsBundle

This bundle - StofDoctrineExtensionsBundle - helps to integrate that library into a Symfony project. Copy the composer require line, find your terminal, and paste!


stof/doctrine-extensions-bundle is now compatible with Symfony 5 - you can use it instead of antishov/doctrine-extensions-bundle fork

composer require antishov/doctrine-extensions-bundle

While that's working, let's go check out the documentation. This is a wonderful library, but its documentation is confusing. So, let's navigate to the parts we need. Scroll down to find a section called "Activate the extensions you want".

As we saw, there are a lot of different, possible behaviors. For performance reasons, when you install this bundle, you need to explicitly say which behaviors you want, like timestampable, by setting it to true.

Contrib Recipes

Move back to the terminal to see if things are done. Oh, interesting! It stopped! And it's asking us if we want to install the recipe for StofDoctrineExtensionsBundle. Hmm... that's weird... because Flex has already installed many other recipes without asking us a question like this.

But! It says that the recipe for this package comes from the "contrib" repository, which is open to community contributions. Symfony has two recipe repositories. The main repository is closely controlled for quality. The second - the "contrib" repository - has some basic checks, but the community can freely contribute recipes. For security reasons, when you download a package that installs a recipe from that repository, it will ask you first before installing it. And, there's a link if you want to review the recipe.

I'm going to say yes, permanently. Now the recipe installs.

Configuring Sluggable

Thanks to this, we now have a shiny new config/packages/stof_doctrine_extensions.yaml file:

# Read the documentation:
# See the official DoctrineExtensions documentation for more details:
default_locale: en_US

This is where we need to enable the extensions we want. We want sluggable. We can use the example in the docs as a guide. Add orm, then default. The default is referring to the default entity manager... because some projects can actually have multiple entity managers. Then, sluggable: true:

# Read the documentation:
# See the official DoctrineExtensions documentation for more details:
default_locale: en_US
sluggable: true

As soon as we do this... drumroll... absolutely nothing will happen. Ok, behind the scenes, the bundle is now looking for slug fields on our entities. But, we need a little bit more config to activate it for Article. Open that class and find the slug property.

Now, go back to the documentation. Another confusing thing about this bundle is that the documentation is split in two places: this page shows you how to configure the bundle... but most of the docs are in the library. Scroll up and find the DoctrineExtensions Documentation link.

Awesome. Click into Down a bit... it tells us that to use this feature, we need to add an @Gedmo\Slug() annotation above the slug field. Let's do it! Use @Gedmo\Slug, then fields={"title"}:

156 lines | src/Entity/Article.php
// ... lines 1 - 5
use Gedmo\Mapping\Annotation as Gedmo;
// ... lines 7 - 10
class Article
// ... lines 13 - 24
// ... line 26
* @Gedmo\Slug(fields={"title"})
private $slug;
// ... lines 30 - 154

That's all we need! Back in ArticleFixtures, we no longer need to set the slug manually (remove it):

66 lines | src/DataFixtures/ArticleFixtures.php
// ... lines 1 - 7
class ArticleFixtures extends BaseFixture
// ... lines 10 - 26
public function loadData(ObjectManager $manager)
$this->createMany(Article::class, 10, function(Article $article, $count) {
// ... lines 32 - 49
// ... lines 51 - 60
// ... lines 62 - 63

Try it out: find your terminal, and load those fixtures!

php bin/console doctrine:fixtures:load

No errors! That's a really good sign, because the slug column is required in the database. Go back to the homepage and... refresh! Brilliant! The slug is clean and clearly based off of the title! As an added benefit, look at how some of these have a number on the end. The Sluggable behavior is making sure that each slug is unique. So, if a slug already exists in the database, it adds a -1 , -2, -3, etc. until it finds an open space.

Hello Doctrine Events

Side note: this feature is built on top of Doctrine's event system. Google for "Doctrine Event Subscriber". You'll find a page on the Symfony documentation that talks about this very important topic. We're not going to create our own event subscriber, but it's a really powerful idea. In this example, they talk about how you could use the event system to automatically update a search index, each time any entity is created or updated. Behind the scenes, the sluggable features works by adding an event listener that is called right before saving, or "flushing", any entity.

If you ever need to do something automatically when an entity is added, updated or removed, think of this system.

Next, let's find out how to rescue things when migrations go wrong!