Many to many relation with ON DELETE CASCADE with Symfony and Doctrine

I want a simple many to many relation with Symfony and Doctrine. This is really a unidirectional one-to-many association can be mapped through a join table as the docs indicate I am using a YAML file for configure this with the following code:

In file Content.orm.yml:

manyToMany:
  comments:
    cascade: ["persist","remove"]
    onDelete: CASCADE
    options:
      cascade:
        remove: true
        persist: true
        #refresh: true
        #merge: true
        #detach: true
    orphanRemoval: false
    orderBy: null
    targetEntity: Comment
    joinTable:
      name: content_comments
      joinColumns:
        content_id:
          referencedColumnName: id
      inverseJoinColumns:
        comment_id:
          referencedColumnName: id
          unique: true

This produce the following SQL commands:

$ php app/console doctrine:schema:update --dump-sql | grep -i "comment\|content"
CREATE TABLE comment (id INT AUTO_INCREMENT NOT NULL, text LONGTEXT NOT NULL, content_id INT NOT NULL, creation_date DATETIME NOT NULL, PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE = InnoDB;
CREATE TABLE contents (id INT AUTO_INCREMENT NOT NULL, user INT DEFAULT NULL, user_id INT NOT NULL,file VARCHAR(255) DEFAULT NULL, INDEX IDX_B4FA11778D93D649 (user), PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE = InnoDB;
CREATE TABLE content_comments (content_id INT NOT NULL, comment_id INT NOT NULL, INDEX IDX_D297CC584A0A3ED (content_id), UNIQUE INDEX UNIQ_D297CC5F8697D13 (comment_id), PRIMARY KEY(content_id, comment_id)) DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE = InnoDB;
ALTER TABLE contents ADD CONSTRAINT FK_B4FA11778D93D649 FOREIGN KEY (user) REFERENCES users (id);
ALTER TABLE content_comments ADD CONSTRAINT FK_D297CC584A0A3ED FOREIGN KEY (content_id) REFERENCES contents (id);
ALTER TABLE content_comments ADD CONSTRAINT FK_D297CC5F8697D13 FOREIGN KEY (comment_id) REFERENCES comment (id);

But as you can see, the FOREIGN KEY instructions doesn't have the parte "ON DELETE CASCADE", even I try to put all the YAML annotations that I found.

Because in code, I am trying to delete a "content" entity and all the "comments" associated with this code:

        $comments = $content->getComments();

        // Remove first the parent
        $entity_manager->remove($content);
        $entity_manager->flush();

        // Remove the childs
        foreach($comments as $comment)
        {
            $entity_manager->remove($comment);
        }

        $entity_manager->flush();

This produce the following exception.

An exception occurred while executing 'DELETE FROM comment WHERE id = ?' with params [1]:\n\nSQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`bb2server`.`content_comments`, CONSTRAINT `FK_D297CC5F8697D13` FOREIGN KEY (`comment_id`) REFERENCES `comment` (`id`))

So, what I am doing wrong? Or how to force to Doctrine to put "ON DELETE CASCADE" in many to many relations?

via Chebli Mohamed