[SOLVED] 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?

My only dirty workaround it drop the SQL query and rebuild myself, but I need that Doctrine create the query in schema:update for avoid my patching:

mysql> show create table content_comments;
+------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table            | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| content_comments | CREATE TABLE `content_comments` (
  `content_id` int(11) NOT NULL,
  `comment_id` int(11) NOT NULL,
  PRIMARY KEY (`content_id`,`comment_id`),
  UNIQUE KEY `UNIQ_D297CC5F8697D13` (`comment_id`),
  KEY `IDX_D297CC584A0A3ED` (`content_id`),
  CONSTRAINT `FK_D297CC584A0A3ED` FOREIGN KEY (`content_id`) REFERENCES `contents` (`id`),
  CONSTRAINT `FK_D297CC5F8697D13` FOREIGN KEY (`comment_id`) REFERENCES `comment` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci |
+------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> ALTER TABLE content_comments DROP FOREIGN KEY FK_D297CC5F8697D13;
Query OK, 0 rows affected (0.04 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> ALTER TABLE content_comments ADD CONSTRAINT FK_D297CC5F8697D13 FOREIGN KEY (`content_id`) REFERENCES `contents` (`id`) ON DELETE CASCADE;
Query OK, 10 rows affected (0.07 sec)
Records: 10  Duplicates: 0  Warnings: 0

Edit: workaround. I need to put the onDelete: CASCADE under the JoinColumns

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
          onDelete: CASCADE
      inverseJoinColumns:
        comment_id:
          referencedColumnName: id
          unique: true
          onDelete: CASCADE