Rails ActiveRecord where or clause

Question

I'm looking to write an ActiveRecord query and this is what I have below. Unfortunately you can't use OR like this. What's the best way to execute? category_ids is an array of integers.

.where(:"categories.id" => category_ids).or.where(:"category_relationships.category_id" => category_ids)

Answer 1

One way is to revert to raw sql...

YourModel.where("categories.id IN ? OR category_relationships.category_id IN ?", category_ids, category_ids)

Answer 2

Keep the SQL out of it and use ARel, like this:

.where(Category.arel_table[:id].in(category_ids).
  or(CategoryRelationship.arel_table[:category_id].in(category_ids))