Question

Let’s say I have 3 main tables:
category, tag, url

category and tag have a MANY_MANY relationship.

tag and url have a MANY_MANY relationship.

I would like from category to retrieve all the linked url.

What is the easiest, most efficient way to do this?

Can I declare a sort of MANY_MANY_MANY relation? Or is this doable in criteria? Or do I have to do it in pure SQL?

I like the idea of Criteria because I will later pass it ‘offset’ and ‘limit’ parameters for pagination purposes…

Answer 1

I may have found a trick: VIEWS

I created the following view:

CREATE VIEW category_url AS
(SELECT DISTINCT category.id AS category_id, url.id AS url_id 
FROM category
LEFT JOIN category_tag ON category_tag.category_id=category.id
LEFT JOIN url_tag ON url_tag.tag_id = category_tag.tag_id
LEFT JOIN url ON url.id = url_tag.url_id)

And I added the following relation to Category:

self::MANY_MANY, 'Url', 'category_url(category_id, url_id)'

I haven’t done extensive testing yet. Comments welcomed.