What is the best way to retrieve the email address of a super admin

Question

Where a component wants to notify a super admin of some event, what is the best way to obtain a super admin email address?

(For background, I originally coded this as a database query, looking for users who were members of the group with title "Super Users". However, I discovered that this only works for an English site as the group title is altered to the local language. It would be possible to look for members of the group with ID 8, but hard coding a number seems a poor solution).

Answer 1

Based on the comment by @Glen Arkell the most sensible thing seems to be to send admin emails to people who have the "receive system email" flag set.

Answer 2

There is no helper function for this but there are a few places in core extensions where this is done. The first part is getting the user groups with super admin permissions:

use Joomla\CMS\Access\Access;
use Joomla\CMS\Table\Table;

// Get root asset ID
$rootId = Table::getInstance('Asset')->getRootId();

// Get root asset rules.
$rules = Access::getAssetRules($rootId)->getData();

// Get root asset user groups.
$groups = $rules['core.admin'] ? $rules['core.admin']->getData() : [];

// Filter out disallowed groups.
$superUserGroups = array_filter($groups);

Once you have these, make a database query to get the emails:

use Joomla\CMS\Factory;

if ($superUserGroups)
{
    $db = Factory::getDbo(true);
    $query = $db->getQuery(true)
        ->select('u.email')
        ->from('#__users AS u')
        ->join(
            'INNER',
            '#__user_usergroup_map AS g',
            'u.id = g.user_id',
        )
        ->whereIn('g.group_id', $superUserGroups);

    // Load the email addresses and remove duplicates.
    $superUserEmails = array_unique($db->setQuery($query)->loadColumn());
}

You can, of course, modify the above query with additional conditions to ensure only unblocked users and/or only users with "Receive System Email" option are selected:

$query->where('u.block = 0')
    ->where('u.sendEmail = 1');

Also instead of removing duplicates with array_unique(), the query can be modified to use DISTINCT or GROUP clause to retrieve a unique list in the first place. But this would probably be slower in most cases.