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Tricks with ArrayCollection

Oh man, the project manager just came to me with a new challenge. Showing all the notes below is great, but they want a new section on top to easily see how many notes have been posted during the past 3 months.

Hmm. In showAction(), we need to somehow count all the recent notes for this Genus. We could start with $recentNotes = $genus->getNotes()... but that's everything. Do we need to finally stop being lazy and make a custom query? Not necessarily.

Remember: getNotes() returns an ArrayCollection object and it has some tricks on it - like a method for filtering! Chain a call to the filter() method and pass this an anonymous function with a GenusNote argument. The ArrayCollection will call this function for each item. If we return true, it stays. If we return false, it disappears.

Easy enough! Return $note->getCreatedAt() > new \DateTime('-3 months');:

122 lines src/AppBundle/Controller/GenusController.php
... lines 1 - 12
class GenusController extends Controller
{
... lines 15 - 57
public function showAction($genusName)
{
... lines 60 - 85
$recentNotes = $genus->getNotes()
->filter(function(GenusNote $note) {
return $note->getCreatedAt() > new \DateTime('-3 months');
});
... lines 90 - 94
}
... lines 96 - 120
}

Next, pass a new recentNoteCount variable into twig that's set to count($recentNotes):

122 lines src/AppBundle/Controller/GenusController.php
... lines 1 - 12
class GenusController extends Controller
{
... lines 15 - 57
public function showAction($genusName)
{
... lines 60 - 90
return $this->render('genus/show.html.twig', array(
'genus' => $genus,
'recentNoteCount' => count($recentNotes)
));
}
... lines 96 - 120
}

In the template, add a new dt for Recent Notes and a dd with {{ recentNoteCount }}:

42 lines app/Resources/views/genus/show.html.twig
... lines 1 - 4
{% block body %}
<h2 class="genus-name">{{ genus.name }}</h2>
<div class="sea-creature-container">
<div class="genus-photo"></div>
<div class="genus-details">
<dl class="genus-details-list">
... lines 12 - 17
<dt>Recent Notes</dt>
<dd>{{ recentNoteCount }}</dd>
</dl>
</div>
</div>
<div id="js-notes-wrapper"></div>
{% endblock %}
... lines 25 - 42

All right - give it a try! Refresh. Six notes - perfect: we clearly have a lot more than six in total.

The ArrayCollection has lots of fun methods on it like this, including contains(), containsKey(), forAll(), map() and other goodies.

Don't Abuse ArrayCollection

Do you see any downsides to this? There's one big one: this queries for all of the notes, even though we don't need them all. If you know you'll only ever have a few notes, no big deal. But if you may have many notes: don't do this - you will feel the performance impact of loading up hundreds of extra objects.

So what's the right way? Finally making a custom query that only returns the GenusNote objects we need. Let's do that next.

Leave a comment!

  • 2016-09-28 Victor Bocharsky

    Well, some Symfony-related courses imply basic Symfony background.

  • 2016-09-28 Maksym Minenko

    I just wonder how it has appeared miraculously between the chapters...

  • 2016-09-28 Victor Bocharsky

    Yo Maksym,

    `$this->get('logger')` or `$this->container->get('logger')`, which is the same, is a service call. Service container returns a Logger object which you can use in order to make some logs in your app. Actually, this course is the 4th in the Symfony 3 track. Please, check the previous one out where we explain some basic things about Service Container and Dependency Injection.

    Cheers!

  • 2016-09-28 Maksym Minenko

    What is this get('logger') line about? There wasn't any in the previous chapter.

  • 2016-05-25 Raphael Schubert

    Yeah.. its really ugly... but it worked... !!! cheers!!!

    i`ll try the second way later... it seems to be good!!

    Thank you for answering me daily!!! i asked around 10 questions... you`re rock!!!

  • 2016-05-25 weaverryan

    Hey Raphael!

    This is the big disadvantage of using Doctrine's array type (array or json_array). You can't *really* query on this - it's ultimately just a string in the database. However, you *can* technically query a "fuzzy" query - but it's a little ugly:


    $this->createQueryBuilder('u')
    ->andWhere('u.roles LIKE :roleSearch')
    ->setParameter('roleSearch', '%ROLE_USER%')
    ->getQuery()
    ->execute();

    If all you need are simple queries - this works in practice. However, if you need to do more complex query, then you'll may need another solution. In this case, I would create a Role entity (it would basically just have a string "role" property) and make a ManyToMany relationship from User to Role. Your User class would look something like this:


    /**
    * @ORM\ManyToMany(targetEntity="Role")
    */
    private $roleObjects;

    // initialize roleObjects to an ArrayCollection in __construct()

    public function getRoles()
    {
    $roles = [];
    foreach ($this->roleObjects as $roleObject) {
    $roles[] = $roleObject->getRole();
    }

    return $roles;
    }

    // add setter and getter for roleObjects like normal

    As you can see, you create a normal ManyToMany relationship, then simply loop over that relationship to return the array of string roles in getRoles() (which is what Symfony's security system wants). Then, you can properly query for exact matches.

    Cheers!

  • 2016-05-25 Raphael Schubert

    Hello!!

    I have a problem... i`m trying select from a field where is stored as array...
    sample.. i Have the [ roles ] field in database.

    Now i need select all users where roles = "ROLE_USER"
    But some of they has: "ROLE_USER", "ROLE_VENDOR", "ROLE_FINANCIAL"

    how can i query for all where contains ROLE_USER?