Active Record Where Not boolean: true - ruby-on-rails

Question

I'm struggling to wrap my mind around an ActiveRecord query.
I'm trying to search my database for GolfRetailer objects with ID's 1..100, that have something (not nil) in their :website field, and that don't have true in their duplicate_domain field.
Here's the query I expected to work:
GolfRetailer.where.not(website: nil, duplicate_domain: true).where(id: 1..100)
I also tried this variant of essentially the same query: GolfRetailer.where.not(website: nil).where(id: 1..100, duplicate_domain: !true)
But both return an empty array, despite there definitely being records that meet those requirements.
When I run GolfRetailer.where.not(website: nil).where(id: 1..100) I get an array, and when I run GolfRetailer.where.not(website: nil, duplicate_domain: nil).where(id: 1..100) I also get an array, but with all records that do have the true duplicate_domain flag, which isn't what I'm looking for.
I'd rather not search for records that have duplicate_domain: nil as that's not always correct (I may not have processed their domain yet).
For clarity, here is the Schema for the Model.
create_table "golf_retailers", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "place_id"
t.string "website"
t.string "formatted_address"
t.string "google_places_name"
t.string "email"
t.boolean "duplicate_domain"
t.index ["duplicate_domain"], name: "index_golf_retailers_on_duplicate_domain"
end
What am I missing to make this query work?

Answer 1

This is happening because in SQL when you do a != TRUE, any NULL values will not be included in the result. This is because the NULL value represents an unknown value, so the DB does not know how to do any comparison operations on an unknown value and therefore they're excluded.
One way to get around this is to use IS DISTINCT FROM:
GolfRetailer
.where(id: 1..100)
.where.not(website: nil)
.where("duplicate_domain IS DISTINCT FROM ?", true)
As others have mentioned, you should also ask yourself if it's really the case that it's ever unknown to you if a GolfRetailer has a duplicate_domain.
If, all GolfRetailers with a duplicate_domain of NULL actually mean they don't have one (false) than you should consider preventing a NULL value for that column entirely.
You can do this by adding a NOT NULL constraint on the column with a change_column database migration.
In order to add the NOT NULL constraint you will first need to make sure all of the data in the column has non-null values.
def change
GolfRetailer.in_batches.update_all(duplicate_domain: false)
change_column_null :golf_retailers, :duplicate_domain
end
If your application is under load, you should also be careful about the potential performance any migration like this might have - notably if you add a NOT NULL constraint with a default value.
Consider using something like the Strong Migrations gem to help find DB migrations that might cause downtime before production.