Regex match unwound array in PHP

Working with Data
,
#1

This question is in PHP.

I have an array element in my document called tags.

This member function gives me an array of MongoDB\Model\BSONDocument :

    public function all_tags(int $ascdesc = self::ASC): array {
        return $this->mongodb_db->fourberie->aggregate([
                    ['$project' => ['tags' => true]],
                    ['$unwind' => '$tags'],
                    ['$group' => ['_id' => '$tags']],
                    ['$sort' => ['_id' => $ascdesc]]
                ])->toArray();
    }

Now I want only those tags that match a regex. The following function yields no documents for any pattern.

Incorrect code deleted - Jack

#2

Figured it out

 /**
     * Returns all matching tags as array of doc.
     * @return array all unique tags as array of doc
     * @param string $pattern pattern to match
     * @param bool $case_sensitive should the match be case sensitive, default = true
     * @param int $ascdesc ASCending or DESCending sort (optional, default self::ASC)
     * @return array of doc for all matching tags
     */
    public function all_tags_matching_regex(string $pattern, bool $case_sensitive = true, int $ascdesc = self::ASC): array {
        return $this->mongodb_db->fourberie->aggregate([
                    ['$project' => ['tags' => true]],
                    ['$unwind' => '$tags'],
                    ['$match' => ['tags' =>
                            $case_sensitive ? (['$regex' => $pattern]) : (['$regex' => $pattern, '$options' => 'i'])
                        ]],
                    ['$group' => ['_id' => '$tags']],
                    ['$sort' => ['_id' => $ascdesc]]
                ])->toArray();
    }