Question

I use Doctrine2 as ORM in a Symfony2 project. I have article and tag entity classes. There are many-to-many relations between them. An article may have many tags and vice versa. There is a joined table, article_tags which just have 2 columns article_id and tag_id, and generated by doctrine. Everything works fine, except, when new article with some tags is added, both new and pre-existing tags are inserted into tag table in which I want to only store unique tags; the article_tags should just relate them.

My article schema:

  manyToMany:
    tags:
      targetEntity: Tag
      cascade: ["persist"]
      joinTable:
    name: article_tag
    joinColumns:
      article_id:
        referencedColumnName: id
    inverseJoinColumns:
      tag_id:
        referencedColumnName: id

Adding unique attribute to tag and ignoring duplicates is not reasonable since there should be relation. I tried to add logic that checks if the tag exists fetch tag data and add it to article:

$article->addTag($existingTag);

It gives the following error:

Catchable Fatal Error: Argument 1 passed to
Seferov\ArticleBundle\Entity\Article::addTag() must be an instance of
Seferov\ArticleBundle\Entity\Tag, null given, called in
/var/www/seferov.local/src/Seferov/ArticleBundle/Repository/TagRepository.php
on line 34 and defined in
/var/www/seferov.local/src/Seferov/ArticleBundle/Entity/Article.php
line 393

Answer 1

You basically need to check if the tag exists. If it does then use it. If not then create one.

public function loadOrg($orgId,$autoCreate = false)
{
    $org = $this->getEntityManager()->find('ZaysoCoreBundle:Org',$orgId);
    if ($org) return $org;

    if (!$autoCreate) return null;
    if (!$orgId)      return null;

    $org = new Org();
    $org->setId($orgId);
    $this->getEntityManager()->persist($org);
    return $org;
}

Be sure to make your tag column unique and to catch exceptions. Possibility that another request might insert the same tag in between the find and the persist.