如何为所有其他类实现数据库类？

Question

I have a large amount of classes for: a main forums class, a forum boards class, and a threads class. These can be thought of as models in the context of my website.

The setup the previous web developer was using creates a new mysqli connection in each one of these classes and connects on instantiation of the class. This means that in the threads page there are 3 different connections for forums, threads, and users. This is obviously not ideal and I think not even optimal.

I worked on a previous project in which I could simply just pass a new instance of the database class to the class I was using, but this isn't ideal because I need to instantiate multiple classes and passing a database instance to each class would defeat the purpose.

In each of these classes, database calls are made so the database object/instance is needed within each class, without having to instantiate it 3+ separate times.

For example, in the threads class you could have:

function get_threads($board_id) {
    return $this->con->query("some query");
}

Does anyone know how I can go about achieving this?

Answer 1

I prefer one database controller that you could get data from as in a factory pattern. In the example below, you could just create one controller and let your components use it as they need.

ex: $threads = new ThreadClass($mysqlConnection);

I hope this helps

# 1. mysql source or "socket" using PDO
class SimpleDatabaseSocket {

    protected static $dbh = false;

    public function connect($database, $user, $pass, $host) {
        $dsn = "mysql:dbname={$database};host={$host}";
        self::$dbh = new PDO($dsn, $user, $pass);
        self::$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }

}

# 2. always use an interface which defines required logic
interface SimpleDatabaseInterface {

    public function onRunQuery($query);
}

# 3. create the accessible controller for inherited & ancillary logic
class SimpleDatabaseController extends SimpleDatabaseSocket implements SimpleDatabaseInterface {

    private $host = "";
    private $base = "";
    private $usr = "";
    private $pwd = "";
    private $table = "";

    # when we create the controller, you MUST pass the connection params
    public function __construct($host, $usr, $pwd, $base) {
        $this->setUsr($usr);
        $this->setPwd($pwd);
        $this->setBase($base);
        $this->setHost($host);
    }

    # mysql host/ip
    public function setHost($host) {
        $this->host = $host;
    }

    # mysql database
    public function setBase($base) {
        $this->base = $base;
    }

    # mysql username
    public function setUsr($usr) {
        $this->usr = $usr;
    }

    # mysql password
    public function setPwd($pwd) {
        $this->pwd = $pwd;
    }
    # allow this controller to switch tables dynamically.
    public function onChangeTable($table) {
        $this->table = $table;
    }

    # connect to the database
    protected function onConnect() {
        $this->connect($this->base, $this->usr, $this->pwd, $this->host);
    }

    # connects to the DB and runs a custom query
    public function onRunQuery($query) {
        try {
            if (!self::$dbh)
                $this->onConnect();
            $result = self::$dbh->query($query);
            $out = $result->fetchAll(PDO::FETCH_ASSOC);
        } catch (PDOException $e) {

        }
        return $out;
    }

}

# exmaple usage
$mysql = new SimpleDatabaseController("HOSTNAME","USERNAME","PASSWORD","DATABASE");
$result = $mysql->onRunQuery("SELECT * FROM TABLE LIMIT 0,2");
print("<pre>" . print_r($result, true) . "</pre>");