symfony - __toString return name from another entity -

let have 2 tables in database : lesson , group. group can have 1 lesson per year.

then have 2 entities, lesson entity :

<?php namespace sifo\adminbundle\entity; use doctrine\orm\mapping orm;  class lesson {     /**     * @var integer     */     private $id;       /**     * @var string     */     private $name;      /**     * set id     *     * @param integer $id     * @return dftgrupmapel     */     public function setid($id)     {         $this->id = $id;         return $this;     }      /**      * id      *      * @return integer       */     public function getid()     {         return $this->id;     } 

and group entity :

<?php namespace sifo\adminbundle\entity; use doctrine\orm\mapping orm;  class group {     /**     * @var integer     */          private $id;      /**      * @var \sifo\adminbundle\entity\mstlesson      */     private $idlesson;      /**     * @var integer     */     private $year;      /**     * set id     *     * @param integer $id     * @return dftgrup     */     public function setid($id)     {         $this->id = $id;         return $this;     }      /**      * id      *      * @return integer       */     public function getid()     {         return $this->id;     }      /**      * set idlesson      *      * @param \sifo\adminbundle\entity\mstlesson $idlesson      * @return dftgrup      */     public function setidlesson(\sifo\adminbundle\entity\mstlesson $idlesson = null)     {         $this->idlesson = $idlesson;         return $this;     }      /**      * idgrup      *      * @return \sifo\adminbundle\entity\mstgrup       */     public function getidlesson()     {         return $this->idlesson;     }      /**     * set year     *     * @param integer $year     * @return dftgrup     */     public function setyear($year)     {         $this->year = $year;         return $this;     }      /**      * year      *      * @return integer       */     public function getyear()     {         return $this->year;     } 

the problem is, in group entity don't have available string show __tostring(). fell not making new name field in group entity , save lesson name there.

lesson.id , group.idlesson foreign key.

how can name field in lesson entity show in __tostring() group without create new field?

thank before.

this orm. group class shouldn't care it's associated lesson's id is... should have reference lesson object itself:

<?php namespace sifo\adminbundle\entity; use doctrine\orm\mapping orm;  class group {     private $id;      // integer     private $lesson;  // lesson object     private $year;    // integer, 

once $lesson lesson object, can refer in group::__tostring():

private function __tostring() {     return $this->lesson->getname(); } 

here's documentation on association mapping, should helpful in mapping relationship between group , lesson:

http://docs.doctrine-project.org/en/2.0.x/reference/association-mapping.html