Many-to-many relationships – Phalcon

If you are working with Phalcon, you will probably need to establish a many-to-many relationship between models. While i was searching in the official documentation, this was not very clear for me at that time. I posted this question on the form, and i got the correct answer.

I will explain you here, step by step. As an example, we will think about the following database structure:

Article table:

CREATE TABLE IF NOT EXISTS `article` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(100) CHARACTER SET latin1 DEFAULT NULL,
  `content` text CHARACTER SET latin1,
  `slug` varchar(160) CHARACTER SET latin1 NOT NULL,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `title` (`title`,`created_at`),
  KEY `slug` (`slug`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=1 ;

Category table:

CREATE TABLE IF NOT EXISTS `category` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET latin1 NOT NULL,
  `slug` varchar(255) CHARACTER SET latin1 DEFAULT NULL,
  `left_node` int(11) NOT NULL,
  `right_node` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_name` (`name`),
  KEY `idx_slug` (`slug`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=1 ;

articles_categories table:

CREATE TABLE IF NOT EXISTS `articles_categories` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `article_id` int(11) NOT NULL,
  `category_id` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `article_id` (`article_id`),
  KEY `category_id` (`category_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

ALTER TABLE `articles_categories`
  ADD CONSTRAINT `articles_categories_ibfk_1` FOREIGN KEY (`article_id`) REFERENCES `article` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `articles_categories_ibfk_2` FOREIGN KEY (`category_id`) REFERENCES `category` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;

Article model:

hasManyToMany(
      "id",
      "Models\ArticlesCategories",
      "article_id",
      "category_id",
      "Models\Category",
      "id",
      array('alias' => 'categories')
    );
  }
}

Category model:

hasManyToMany(
      "id",
      "Models\ArticlesCategories",
      "category_id",
      "article_id",
      "Models\Article",
      "id",
      array('alias' => 'articles')
    );
  }
}

ArticlesCategories model:

belongsTo('category_id', 'Models\Category', 'id', 
      array('alias' => 'category')
    );
    $this->belongsTo('article_id', 'Models\Article', 'id', 
      array('alias' => 'article')
    );
  }
}

Easy, huh ? See the original post. I hope this was helpful 🙂