Model_blog_entity.php

class Model_Blog_Entity extends Model_Entity {
  protected $_id;
  protected $_title;
  protected $_post;
  protected $_author;

  public function getId() {
    return $this->_id;
  }
  public function setId() {
    $this->_id = $id;
  }

  ...
}

Model_blog_mapper.php

class Model_Blog_Mapper extends Model_Mapper {
  protected $_tableName = “blogposts”;
  protected $_primaryKey = “id”;

  protected function _toArray(Model_Entity $obj) {
    $data = array();
    $data[‘id’] = $obj->getId();
    $data[‘title’] = $obj->getTitle();
    ...
    return $data;
  }

  protected function _fromArray(array $data) {
    $obj = new Model_Blog_Entity();
    $obj->setId($data[‘id’]);
    $obj->setTitle($data[‘title’]);
    ...
    return $obj;
  }

}

model_entity.php

abstract class Model_Entity {
}

model_mapper.php

abstract class Model_Mapper {
  protected $_tableName = ‘’;
  protected $_primaryKey = ‘’;
  protected $_table;

  function __construct() {
    $this->_table = new Zend_Db_Table($this->_tableName);
  }

  function findByPk($value) {
    $select = $this->_table->select()->where($this->_primaryKey . ‘ = ?’, $value);
    $row = $select->fetchRow($select);
    if ($row == null) return null;
    return $this->_fromArray($row->toArray());
  }

  public function fromArray(array $data) {
    return $this->_fromArray($data);
  }

  abstract protected function _toArray(Model_Entity $obj);
  abstract protected function _fromArray(array $data);

  function save(Model_Entity $obj) {
    $data = $this->_toArray($obj);

    if ($obj->getId() == 0) {
  $row = null;
} else {
  // Check if record exists on PK.
      $select = $this->_table->select()->where($this->_primaryKey.' = ?' , $obj->getId());
      $row = $this->_table->fetchRow($select);
    }

    if ($row == null) {
      // INSERT, record does not exists
      $this->_table->insert($data);
    } else {
      // UPDATE, record does exists
      $where = $this->_table->getAdapter()->quoteInto($this->_primaryKey.' = ?', $obj->getId());
      $this->_table->update($data, $where);
    }
  

  }

}