So let's say I have Post, Category and Categorizations models.
A post can have many categories through categorizations.
Now, how can I pull out all the posts that match at least one item of an array of categories?
Example:
Post 1 has categories 2,5,6
Post 2 has categories 1,5,9
Post 3 has categories 2,4,8
Find posts that match 3,5
I want the posts 1 and 2 to be returned.
Thanks!
Assuming that Categorization is a join model for Post and Category:
Post.joins(:categorizations).where(:categorizations => {:category_id => [3, 5]})
If it's not, and Categorization actually has_many :categories then:
Post.joins(:categories).where(:categories=> {:id => [3, 5]})
Note that the second method will work in the first case as well, however it will require 2 SQL joins and thus may not perform as well.
