(Symfony 4) Unable to access a const array's element in twig

Question

I have a const array that I need to access in twig, here is my constants class:

class Constants{

    public const NOTIFICATIONS_LIKE_POST = 0;
    public const NOTIFICATIONS_COMMENT_POST = 1;
    public const NOTIFICATIONS_REPLY_COMMENT = 2;
    public const NOTIFICATIONS_POSTED_NEW_POST = 3;
    public const NOTIFICATIONS_POSTED_NEW_PHOTO = 4;
    public const NOTIFICATIONS_POSTED_NEW_VIDEO = 5;
    public const NOTIFICATIONS_POSTED_NEW_GALLERY = 6;

    public NOTIFICATIONS_ARRAY= array(
    self::NOTIFICATIONS_LIKE_POST => " liked your ",
    self::NOTIFICATIONS_COMMENT_POST => " commented on your ",
    self::NOTIFICATIONS_REPLY_COMMENT => " replied to your ",
    self::NOTIFICATIONS_POSTED_NEW_POST => " posted a new ",
    self::NOTIFICATIONS_POSTED_NEW_PHOTO => " posted a new ",
    self::NOTIFICATIONS_POSTED_NEW_VIDEO => " posted a new ",
    self::NOTIFICATIONS_POSTED_NEW_GALLERY => "posted a new "
    );

}

Here's what it looks like when I want to add it in my twig:

{% for notification in notifications %}

    <div class="notice" onclick="window.open('single-post.html');">
        <div class="header">
            <img src="{{ getAvatar(notification.fromUser) }}" width="128" class="avatar">

            <div class="content">
                <a href="../profile.html" class="user">{{ notification.fromUser.username }}</a>
                <!-- so specifically the following line -->
                {{ dump(constant("App\\Constants::NOTIFICATIONS_ARRAY[" ~ notification.activity ~ "]")) }}

                <div class="footer">
                    notification.time
                </div>
            </div>
        </div>
    </div>

{% endfor %}

Just to show you that twig can "see" this array, here is the output of:

{{ dump(constant("App\\Constants::NOTIFICATIONS_ARRAY")) }}

However when I try to access this array with an index (here is what the code looks like:)

<!-- In this case notification.activity is 2 --> 
{{ dump(constant("App\\Constants::NOTIFICATIONS_ARRAY[" ~ notification.activity ~ "]")) }}

I get the following error:

An exception has been thrown during the rendering of a template ("Warning: constant(): Couldn't find constant App\Constants::NOTIFICATIONS_ARRAY[2]").

Maybe it's just a PHP syntax thing? I don't know why I can't access a specific element of my const array.

Answer 1

The array index isn't part of the name of the constant. The constant is an array:

{{ dump(constant("App\\Constants::NOTIFICATIONS_ARRAY")[notification.activity]) }}