Associations in ActiveRecord "not"

May 1, 2013 - 1 minute read -
activerecord rails4

While working with Rails 4 today I was attempting to use the new .not method of ActiveRecord. This method is similar to the jQuery .not method as it allows you to filter your result set where a particular attribute of your result does NOT match what you pass in as .not’s argument. The syntax is:

Post.where.not(author: author)

This will also insure that when author is nil the proper sql syntax of IS NOT NULL is used.

I couldn’t find much out on the internet about this method aside from what I had seen on CodeSchool’s Rails 4: Zombie Outlaws and I needed to perform a “not” based on an association. The code school example only covered the simple scenario of a not based on a field on the model you are performing the not on. Here is what worked for associated models:


scope :purchasable, ->{
    .where.not(table3: {table2_id: nil})
    #.where('table3.table2_id IS NOT NULL')

Long story short, you need to use nested hashes to utilize associations in your not method calls.