Tips/resources/patterns for learning to implement a basic ORM [closed]

Answer 1

A simple ORM can be built using __get() and __set() and a couple of custom methods (possibly using __call()), here is a simple pseudo-code:

class ORM
{
  private $table = null;
  private $fields = array();

  function __construct($table)
  {
    $this->table = $table;
  }

  function __get($key)
  {
    return isset($this->fields[$key]) ? $this->fields[$key] : false;
  }

  function __set($key, $value)
  {
    $this->fields[$key] = $value;
  }

  function load($id, $field = 'id')
  {
    // populate $this->fields with SELECT * FROM $this->table WHERE $field = $id;
  }

  function save()
  {
    if (isset($this->fields['id']))
    {
      // UPDATE $this->table SET $this->fields;
    }

    else
    {
      // INSERT INTO $this->table $this->fields;
    }
  }
}

$user = new ORM('user');

$user->name = 'name';
$user->pass = '1337';

$user->save();

This is just a basic example to get you started. You could add further logic using the __call() magic method to fetch results by other fields than id for instance.

Bear in mind that the example I gave doesn't handle relations, that's where various ORM implementations really differ, however I normally don't trust any ORM to handle relations for me since they tend to be way slower and not produce efficient queries.