Ruby on Rails ActiveRecord query using a join

Question

I have a User model and the user has a relationship which is has_many pets. I want to be able to write an ActiveRecord query where I can select all users with a pet that doe

Answer 1

This should work:

User.joins(:pets).where("pets.name != 'fluffy'")

Also you might want to read the following part (on joins) on the official RoR guidelines.

Answer 2

The cleanest way without SQL injection vulnerability is using query parameters:

User.joins(:pets).where("pets.name != ?", "fluffy")

Some database drivers will utilize prepared statements for above to reuse database query plan. In such case the database doesn't have to analyze query again when only param value varies.

Answer 3

In rails 4 you can make this even more clear:

User.joins(:pets).where.not(pets: { name: 'fluffy' })