在Doctrine 2中的多个实体上的标签

Question

I'm trying to create a simple tagging system with Doctrine, but i'm not sure how to build the entity relationships. A User that can have multiple Tag would be a simple ManyToMany association, but what happens when i have two or more entities that can be tagged?

I have three entities: User, Group and Application. All three entities can be tagged. How can i relate those three with the Tag entity?

Answer 1

You should map Tag entity in User, Group and Application entity, if you are using annotations then the code in each of mentioned entities should look similar to this:

/**
 * @ORM\Table(name="class_name")
 * @ORM\Entity
 */
class ClassName {
    // Definition of other attributes skipped

    /**
     * @ORM\ManyToMany(targetEntity="Tag")
     */
    private $tags;

    public function __construct(){
         $this->tags = new ArrayCollection();
    }

    // Definition of other methods skipped

    public function getTags(){
        return $this->tags;
    }

    public function setTags($tags){
        $this->tags = $tags;
    }

    public function addTag(Tag $tag){
        $this->tags->add($tag);
    }

    public function removeTag(Tag $tag){
        $this->tags->remove($tag);
    }
}