ORM implementation

BaseModel.php

<?php
/**
 * ORM implementation.
 *
 * BaseModel realizes all logic for managing database connections and
 * work with entities which stored in database as plain PHP objects.
 *
 * This implementation supports object relations:
 *
 * * one to one
 * * many to one
 *
 * Not realized:
 *
 * * model validations(use database constraints)
 * * many to many object relation
 *
 * @author Miroslav Kyurchev <[email protected]>
 * @copyright 2013 Miroslav Kyurchev
 * @depends Inflector
 * @license MIT
 * @since 0.1
 * @version 0.1
 */
class BaseModel
{
  private static $db;

  protected $attributes = array();

  /**
   * Connects to database.
   *
   * @access public
   * @static
   * @return PDO Object representing a connection to a database
   */
  static function db()
  {
    if (!isset(self::$db)) {
      if (isset($_ENV["DATABASE_URL"])) {
        extract(parse_url($_ENV["DATABASE_URL"]));

        $dsn = "pgsql:host=$host;dbname=".substr($path, 1).";user=$user;password=$pass";
      } else {
        $dsn = "pgsql:host=localhost;dbname=wt_lab2_test;user=postgres;password=postgres";
      }

      self::$db = new PDO($dsn);
    }

    return self::$db;
  }

  /**
   * Returns name of table corresponding current model.
   * @access public
   * @static
   * @return string Name of the table corresponding current model
   */
  static function table_name()
  {
    return Inflector::tableize(get_called_class());
  }

  /**
   * Gets all records.
   * @access public
   * @static
   * @return array Objects corresponiding table records
   */
  static function all()
  {
    $query = 'SELECT * FROM '.self::table_name();

    $reflection = new ReflectionClass(get_called_class());

    $sth = self::db()->prepare($query);
    $sth->setFetchMode(PDO::FETCH_INTO, $reflection->newInstance());
    $sth->execute();

    return $sth->fetchAll(PDO::FETCH_INTO);
  }
  /**
   * Finds record by given column.
   * @access public
   * @static
   * @param int $name Name of column to find by
   * @param int $value Column value to find
   * @return object Object corresponding record with given id
   */
  static function find_by($name, $value)
  {
    $query = 'SELECT * FROM '.self::table_name().' WHERE '.$name.'=?';

    $reflection = new ReflectionClass(get_called_class());

    $sth = self::db()->prepare($query);
    $sth->setFetchMode(PDO::FETCH_INTO, $reflection->newInstance());
    $sth->execute(array($value));

    return $sth->fetch(PDO::FETCH_INTO);
  }


  /**
   * Finds record by id.
   * @access public
   * @static
   * @param int $id Id of record to find
   * @return object Object corresponding record with given id
   */
  static function find($id)
  {
    return self::find_by('id', $id);
  }

  /**
   * Constructs object and saves it to database.
   * @access public
   * @static
   * @param array $attributes Attributes to save in databse
   * @return object Object corresponding database record
   */
  static function create($attributes)
  {
    $attributes = array_filter($attributes);
    unset($attributes['id']);

    $columns = array_keys($attributes);
    $placeholders = array_map(function ($elem) {
      return ":$elem";
    }, $columns);

    $query = 'INSERT INTO '.self::table_name().' ('.join(', ', $columns).') values ('.join(', ', $placeholders).')';

    $sth = self::db()->prepare($query);

    if ($sth->execute($attributes))
    {
      $reflection = new ReflectionClass(get_called_class());
      return $reflection->newInstance($attributes);
    } else {
      return false;
    }
  }

  /**
   * Deletes record with given id from table
   * @access public
   * @static
   * @param int $id Id of record to delete
   * @return bool Result of executing query
   */
  static function delete($id)
  {
    $query = 'DELETE FROM '.self::table_name().' WHERE id=?';
    $sth = self::db()->prepare($query);
    return $sth->execute(array($id));
  }

  /**
   * Finds all objects of the given model which are associated with current
   * @access public
   * @param string $class_name Name of the model to find
   * @return array Objects which are associated with current
   */
  function find_assoc($class_name)
  {
    $table_name = Inflector::tableize($class_name);
    $column_name = Inflector::underscore(get_called_class());
    $query = 'SELECT * FROM '.$table_name.' WHERE '.$column_name.'_id=?';

    $reflection = new ReflectionClass($class_name);

    $sth = self::db()->prepare($query);
    $sth->setFetchMode(PDO::FETCH_INTO, $reflection->newInstance());
    $sth->execute(array($this->attributes['id']));

    return $sth->fetchAll(PDO::FETCH_INTO);
  }

  /**
   * Updates specified attributes of object in database
   * @access public
   * @param array $attributes Attributes to update
   * @return bool Result of executing query
   */
  function update($attributes)
  {
    $attributes = array_filter($attributes);
    $attributes['id'] = $this->attributes['id'];

    $columns = array_keys($attributes);
    $columns = array_diff($columns, array('id'));
    $columns = array_map(function ($elem) {
      return "$elem=:$elem";
    }, $columns);

    $query = 'UPDATE '.self::table_name().' SET '.join(', ', $columns).' WHERE id=:id';

    $sth = self::db()->prepare($query);
    return $sth->execute($attributes);
  }

  /**
   * Saves new object to database or updates existing
   * @access public
   * @return mixed Object corresponding database record or result of executing query
   */
  function save()
  {
    if ((!isset($this->attributes['id']) && count($this->attributes) > 0) || count($this->attributes) > 1) {
      if (isset($this->attributes['id']))
      {
        return $this->update($this->attributes);
      } else {
        return self::create($this->attributes);
      }
    } else {
      trigger_error('Not specified attributes to save', E_USER_NOTICE);
    }
  }

  /**
   * Sets object properties as elements of attributes array
   * @param string $name Name of property
   * @param mixed $value Value of property
   * @return void
   */
  function __set($name, $value)
  {
    $this->attributes[$name] = $value;
  }

  /**
   * Gets object's attributes or associated objects
   * @param string $name Name of property
   * @return mixed Value of property or associated objects
   */
  function __get($name)
  {
    if (array_key_exists($name, $this->attributes)) {
      return $this->attributes[$name];
    } elseif (array_key_exists($name.'_id', $this->attributes)) {
      $class = Inflector::classify($name);
      return $class::find($this->attributes[$name.'_id']);
    } else {
      $class = Inflector::classify($name);
      $result = $this->find_assoc($class);

      if (!empty($result)) {
        return $result;
      } else {
        $trace = debug_backtrace();
        trigger_error('No objects associated or undefined attribute '.$name.' in '.$trace[0]['file'].' on line ' . $trace[0]['line'], E_USER_NOTICE);
        return null;
      }
    }
  }

  /**
   * Initializes object
   * @param array $attributes Attributes to save in databse
   * @return void
   */
  function __construct($attributes = array())
  {
    $this->attributes = $attributes;
  }

  /**
   * Deletes corresponding record from database
   * @access public
   * @return bool Result of executing query
   */
  function destroy() {
    if (isset($this->attributes['id']))
      self::delete($this->attributes['id']);
  }
}
?>