Looking at the tables (aros, acos) generated by the ACL component and for example the Favorites plugin by CakeDC I see the favorites table with the fields Favorite.user_id, Favorite.model and Favorite.foreign_key.
The last two combined are replacing the good old Favorite.post_id (presuming model has the value 'Post'). It is in a way a HABTM pivot table with a dynamic modelname on one side.
I can see the general and useful idea here but would like to know more about the application of it.
My question(s):
- Does this pattern have a name?
- How does this work code-wise? I can see the abstract principle, but what kind of model-code is needed to make this work? Does it involve a patchwork of queries, or does this allow for a smooth one-query implementention? E.g.: I’d like to fetch all marked-as-favorite Posts in the system and their related Users in one go.
- And does this work both ways? (querying from both the Post model as well as the User model)
I’d like to work towards an abstraction where I put a behavior in place to take care of this pattern.
I did look into the CakeDC code but could not figure out the principle. It’s a little too cryptic for my current knowledge. Hence my question here.
kind regards,
Bart
http://en.wikipedia.org/wiki/Junction_table aka Join Table.
It is just a regular join table, that’s all. You can simply rely on what CakePHP is building up when using the HABTM assocs or refine your query by using joins. See http://book.cakephp.org/2.0/en/models/associations-linking-models-together.html#joining-tables.
The model field is not needed in that “pattern” but allows you to have just one join table that can be used for many different tables/models. For example instead of having tags and users and posts associated by tags_posts and tags_users we simply use the same table and filter by the model field.
Yes if you set the HABTM association up in both models.
Thanks for using our plugins. 😉