Help with procedural MySQLi class migration to object-oriented

Hello, good afternoon.

I started migrating a MySQLi class of procedural to Object Oriented and two functions of this class left me in doubt.

During the migration of the fetchRow and fetch_array functions I was struck by a strong doubt, since in the procedural class it is pretty weird and I did not find a way to do it similar to the object-oriented version.

function &fetchRow($sql, $type = 'DBARRAY_ASSOC') {
    $this->sql = & $sql;
    $queryresult = $this->execute_query(true, $this->connection_master);
    $returnarray = $this->fetch_array($queryresult, $type);
    $this->free_result($queryresult);
    return $returnarray;
}

function fetch_array($queryresult, $type = 'DBARRAY_ASSOC') {
    $result = @$this->functions['fetch_array']($queryresult, $this->fetchtypes["$type"]);
    return $result;
}

I'll also leave here the code for the execute_query function that appears in the code:

function &execute_query($buffered = true, &$link) {
    $this->connection_recent = & $link;

    if ($queryresult = $this->functions[$buffered ? 'query' : 'query_unbuffered']($link, $this->sql)) {
        // unset $sql to lower memory .. this isn't an error, so it's not needed
        $this->sql = '';

        return $queryresult;
    } else {
        // unset $sql to lower memory .. error will have already been thrown
        $this->sql = '';
    }
}

And here are my OOP codes that are not working correctly ...

public function fetchRow($query, $type = MYSQLI_ASSOC) {
    $this->Process = self::query($query);
    return $this->Process->fetch_array($type);
}

public function fetch_array($query, $type = MYSQLI_ASSOC) {
    $this->Process = $this->_Engine->query($query);
    return $this->Process->fetch_array($type);
}

The codes were the same because I had no idea how it was done in the procedural version.

Thank you in advance!