ActiveRecord where.not is not working/ weird behav

问题:

User has_many Plans. I'm trying to find the IDs of all Users that do NOT have a Plan with status of "canceled". Would love to know what's explaining the behavior below.

For context, what should be returned is this:

User.select { |u| u.plans.select { |p| p.status != "canceled" }.count > 0 }.map(&:id)
# => [27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63]

Here's what I'm getting:

# statement 1
User.joins(:plans).where.not("plans.status" => "canceled").map(&:id)
# User Load (0.3ms)  SELECT "users".* FROM "users" INNER JOIN "plans" ON "plans"."user_id" = "users"."id" WHERE ("plans"."status" != 'canceled')
# => [44]

# statement 2
User.joins(:plans).where("plans.status != ?", "canceled").map(&:id)
# User Load (0.3ms)  SELECT "users".* FROM "users" INNER JOIN "plans" ON "plans"."user_id" = "users"."id" WHERE (plans.status != 'canceled')
# => [44]

# statement 3
User.joins(:plans).where("plans.status == ?", nil).map(&:id)
# User Load (0.3ms)  SELECT "users".* FROM "users" INNER JOIN "plans" ON "plans"."user_id" = "users"."id" WHERE (plans.status == NULL)
# => []

# statement 4
User.joins(:plans).where("plans.status" => nil).map(&:id)
# User Load (0.7ms)  SELECT "users".* FROM "users" INNER JOIN "plans" ON "plans"."user_id" = "users"."id" WHERE "plans"."status" IS NULL
# => [27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 41, 44, 42, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 61, 60, 62, 63]

Questions:

1. Why are statement 3 and 4 not returning the same result?
2. Why are statement 1 and 2 (fortunately these are the same and are returning the same result) not returning the same result as statement 4? For context, I'd rather not search on nil, but on "canceled". And I can confirm that all plans have either a status of nil or "canceled"

UPDATE PER REQUEST

# plan with nil status
Plan.where(status: nil).first
# => <Plan id: 1, zipcode: "94282", selected_plan: 1, meal_type: "Chef's choice (mixed)", most_favorite: "", least_favorite: "", allergies: "", start_date: "2015-05-27 00:00:00", delivery_address: "d", delivery_instructions: "", phone1: "10", phone2: "222", phone3: "2222", agree_tos: true, user_id: 20, created_at: "2015-05-24 05:18:40", updated_at: "2015-06-21 04:54:31", stripe_subscription_id: nil, stripe_invoice_number: nil, cancel_reason: nil, cancel_reason_other: nil, nps: nil, nps_open: nil, cancel_open: nil, status: nil, referred_by_code: nil>

# plan with canceled status
Plan.where(status: "canceled").first
# => <Plan id: 20, zipcode: "12345", selected_plan: 5, meal_type: "Meat (with veggies)", most_favorite: "", least_favorite: "", allergies: "", start_date: "2015-06-08 00:00:00", delivery_address: "asdf", delivery_instructions: "", phone1: "333", phone2: "333", phone3: "3333", agree_tos: true, user_id: 38, created_at: "2015-06-01 21:39:54", updated_at: "2015-06-23 06:23:10", stripe_subscription_id: "sub_6OKkJoNx2u8ZXZ", stripe_invoice_number: 0, cancel_reason: nil, cancel_reason_other: "", nps: 6, nps_open: "", cancel_open: "", status: "canceled", referred_by_code: nil> 

回答1:

Answer to Question 1:

You missed the concept that in conditional sql, the arguments that follow the condition are replaced in place of ? not compared to. So, replace the double == with =.

User.joins(:plans).where("plans.status = ?", nil).map(&:id)