php - Doctrine - Add foreign key pointing to 2 target entities -

i have 3 entities; blog, project , comment. block , projects both have comments. want foreign key ref_id in comment point either blog or project using ref_type value. here entities

class blog {   ...   protected $id;   ...   protected $title;   ... }  class project {    ...    private $id;    ...    private $title; }  class comment {   ...   protected $id;    /**    * @orm\column(type="string")    */   protected $ref_type;    /**    * @orm\manytoone(targetentity="**project,blog**", inversedby="comments")    * @orm\joincolumn(name="ref_id", referencedcolumnname="id")   */   protected $ref_id;   } 

i new in doctrine might simple can find solution. google came across mapped superclasses not sure how relevant issue.

yes, solution subclassing blog , project.

prepare db

at first place, can make subclass inherent table. let super class named "commentable".

create table commentable( int id_commentable not null primary key auto_increment, title varchar(200) not null, c_type vachar(100) not null); 

and then, every commentable has custom fields:

/* blog table */ create table blog(id_commentable int not null primary key, description text); /* project table */ create table project(id_commentable int not null primary key, location text); 

note 3 tables above have same primary key name. mandatory

the comments table has relationship commentable table

create table comments(id_comment int not null primary key auto_increment, comment text, commentable_id int not null); 

create superclass , children

according tables time start build entities.

commentable superclass

/**  * @entity  * @inheritancetype("joined")  * @discriminatorcolumn(name="c_type", type="string")  */ abstract class commentable {      /**      * @id      * @column(type="integer", nullable=false, name="id_commentable")      * @generatedvalue(strategy="auto")      */     protected $id;      /**      * @column(type="string")      */     protected $title;      /**      * @onetomany(targetentity="comment", mappedby="commentable")      **/     protected $comments;      function getcomments(){ return $this->comments; } 

blog

/**  * @entity  * @table(name="blog")  */  class blog extends commentable{      /**      * @column(type="string")      */     protected $title; 

project

/**  * @entity  * @table(name="project")  */  class project extends commentable{      /**      * @column(type="string")      */     protected $location; 

comments

take in count comments point commentable entity , not children.

/**  * @entity  * @table(name="comments")  */  class comment{      /**      * @manytoone(targetentity="commentable", inversedby="comments")      * @joincolumn(name="comment_id", referencedcolumnname="id_comment")      **/     protected $commentable;      /**      * @column(type="string")      */     protected $comment; 

usage

for example, if want project comments, do:

// knowing id 3 project $project = em->find('models\project', 3); $comments = $project->getcomments(); 

or if prefer comments not matter type:

$commentable = em->find('models\commentable', 3); $comments = $commentable->getcomments(); 

both examples above return same list of comments;