php - Doctrine2 / PostgreSQL - Selection error with a nullable relation -

in zf2 application, have 2 doctrine2 entities : product , partner

because in cases product doesn't need partner, there nullable manytoone relation between product , partner.

it works if partner provided in form (dropdown). if not, have error :

an exception occurred while executing 'select t0.id id1, t0.title title2 partners t0 t0.id = ?' params [""]:  sqlstate[22p02]: invalid text representation: 7 error:  invalid input syntax integer: ""` 

the entities :

/**  * @orm\entity  * @orm\table(name="products")  */ class product extends abstractentity {     /* ... */      /**      * @orm\manytoone(targetentity="partner", inversedby="products", cascade={"persist", "merge"})      * @orm\joincolumn(name="partner_id", referencedcolumnname="id", nullable=true)      */     protected $partner;      /* ... */      /**      * @return partner      */     public function getpartner()     {         return $this->partner;     }      /**      * @param partner $partner      *      * @return $this      */     public function setpartner(partner $partner)     {         $this->partner = $partner;          return $this;     }      /* ... */ }    /**  * @orm\entity  * @orm\table(name="partners")  */ class partner extends abstractentity {     /* ... */      /**      * @orm\onetomany(targetentity="product", mappedby="partner", cascade={"persist", "merge", "remove"})      **/     protected $products;      /* ... */      public function __construct()     {         $this->products = new arraycollection();     }      /* ... */      /**      * @param product $product      *      * @return $this      */     public function addproduct(product $product)     {         $this->products[] = $product;         $product->setpartner($this);          return $this;     }      /**      * @param $products      *      * @return $this      */     public function addproducts($products)     {         foreach ($products $product)         {             $this->addproduct($product);         }          return $this;     }      /**      * @param null $products      *      * @return $this      */     public function removeproducts($products = null)     {         if (!$products)         {             $products = $this->getproducts();         }          foreach ($products $product)         {             if (is_object($product))             {                 $this->products->removeelement($product);             }             else $this->products->remove($product);         }          return $this;     }      /**      * @return mixed      */     public function getproducts()     {         return $this->products;     }      /**      * @param mixed $products      *      * @return $this      */     public function setproducts($products)     {         $this->products = $products;          return $this;     }      /* ... */ } 

any appreciated.

thanks @hkulekci answer.

i updated input filter :

public function getinputfilterspecification() {     return [         'partner' => ['required' => true],         /* ... */     ]; } 

to :

public function getinputfilterspecification() {     return [         'partner' => [             'required' => true,             'continue_if_empty' => true,             'filters' => [                 ['name' => 'null']             ]         ],         /* ... */     ]; }