Re: [PHP] PHP5 OOP

[Matthew Sims]

> Hello, I'm trying to get the hang of OOP here but can't quite figure
> out how to relate these classes.  I've got one for the main project,
> one for the database, and one for a user.  Somehow I need to get the
> user access to the database, without cumbersome constructor calls
> involving a copy of the instance of the class itself.

<snip class>

>
> I tried extending the user class from the project class, but that
> didn't work, because the $db var was empty.  I tried changing it to
> static, but it didn't inherit the $db variable for some reason.  So,
> how can I make this work, so I can write a bunch of classes that can
> blindly use $this->db or something similar without having to worry
> about setting it in the constructor?  I thought about setting it as a
> global, but that didn't seem very... OOP.
>
> --
> Joel Kitching
> http://midgardmanga.keenspace.com/
>

This is a great class to learn how OO works in PHP5.

class DB_Mysql {

  protected $user;      // Database username
  protected $pass;      // Database password
  protected $dbhost;    // Database host
  protected $dbname;    // Database name
  protected $dbh;       // Database handle

  public function __construct($user, $pass, $dbhost, $dbname) {
        $this->user = $user;
        $this->pass = $pass;
        $this->dbhost = $dbhost;
        $this->dbname = $dbname;
  }

  protected function connect() {
        $this->dbh = @mysql_connect($this->dbhost, $this->user, this->pass);

        if (!is_resource($this->dbh)) {
          throw new Exception("Cannot connect to the database");
        }

        if (!mysql_select_db($this->dbname, $this->dbh)) {
          throw new Exception("No such database by that name");
        }
  }

  public function execute($query) {
        if (!$this->dbh) {
          $this->connect();
        }

        $ret = mysql_query($query, $this->dbh);

        if (!$ret) {
          throw new Exception("There is an issue with the query string");
        } elseif (!is_resource($ret)) {
          return TRUE;
        } else {
          $stmt = new DB_MysqlStatement($this->dbh, $query);
          $stmt->result = $ret;
          return $stmt;
        }
  }

}

class DB_MysqlStatement {

  public $result;
  public $query;
  protected $dbh;

  public function __contruct($dbh, $query) {
        $this->query = $query;
        $this->dbh = $dbh;

        if (!is_resource($dbh)) {
          throw new Exception("Cannot connect to the database");
        }
  }

  public function fetch_row() {
        if (!$this->result) {
          throw new Exception("There is an issue with the query string");
        }
        return mysql_fetch_row($this->query);
  }

  public function fetch_assoc() {
        return mysql_fetch_assoc($this->result);
  }

  public function fetchall_assoc() {
        $retval = array();
        while ($row = $this->fetch_assoc()) {
          $retval[] = $row;
        }
        return $retval;
  }

}

Then call it like:

$dbhObj = new DB_Mysql("user","passwd","localhost","DBname");

$query = "SELECT * FROM user WHERE id = ' . $id";

$result = $dbhObj->execute($query);

while ($row = $result->fetch_assoc()) {
  //do stuff with $row array
}

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