php - phpdoctrine save collection of differents entities -

i have interface:

interface product {     function getamount(); } 

and php doctine entities:

/**  * @orm\table(name="orders")  * @orm\entity  */ class order {     private $products = array();      public function addproduct(product $product){         $this->products[] = $product;     }      public function getproducts() {         return $this->products;     }      function getamount() {         $amount = 0;         foreach ($this->products $product) {             $amount += $product->getamount();         }          return $amount;     } } /**  * @orm\table(name="books")  * @orm\entity  */ class book implements product {     function getamount() {         return 1;     } } /**  * @orm\table(name="pens")  * @orm\entity  */ class pen implements product {     function getamount()     {         return 2;     } } 

book, pen - different entities , table. how implement relationship order::products collection of books, pens, etc(for save in database)?

i understand 2 solutions problem. first when saving(and loading) database manually convert relationship map(array of entities names , ids). decision not like. , second correct architecture. not know how. have ready-made solution ... please.

i'am not sure can way.

• whether define separate entity poduct , add column product_type tell whether book, pen or ever.

  in entity product property should defined enum , can tricky(depends on use besides doctrine)

• or make each product type (what can pretty fast nightmare). i'd guess have manytomany relation. should smth. that.

in order

 /**  * @manytomany(targetentity="book")  * @jointable(name="order_book",  *      joincolumns={@joincolumn(name="book_id", referencedcolumnname="id")},  *      inversejoincolumns={@joincolumn(name="order_id", referencedcolumnname="id")}  *      )  */  protected $book;   /**  * @manytomany(targetentity="pen")  * @jointable(name="order_pen",  *      joincolumns={@joincolumn(name="pen_id", referencedcolumnname="id")},  *      inversejoincolumns={@joincolumn(name="order_id", referencedcolumnname="id")}  *      )  */  protected $pen; 

and in book:

  /*   * @manytomany(targetentity="order", mappedby="book")   */   protected $order; 

with pen , others same way.