Rails 5.1: Passing in array to where query does not search across multiple values

Question

I'm in the process of upgrading my Rails app to 5.1.x. I've noticed that when I try a query such as:
Book.where(genre: ['mystery', 'romance']).count,
the SQL generated is
SELECT COUNT(*) FROM "books" WHERE "books"."genre" = $1 [["genre", "[\"mystery\", \"romance\"]"]]
instead of what you'd expect:
SELECT COUNT(*) FROM "books" WHERE "books"."genre" IN ('mystery', 'romance')

What has changed? Is there some way to keep the old behavior? The 5.1.3 doesn't suggest that this functionality has changed: http://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-where

Thanks!

Answer 1

Update: Found my problem! Thanks to Robert's question the other day, I realized my problem is because genre is saved to the DB as a string but is used as a Genre object. Previously, I'd been using serialize :genre Genre, but for some reason it wasn't using the right values in the where clause properly.

I created a new GenreType < ActiveRecord::Type and added attribute :genre GenreType.new and voila!

http://api.rubyonrails.org/classes/ActiveRecord/Attributes/ClassMethods.html