ActiveRecord where.not 不工作/奇怪的行为

Question

用户has_many 计划。我正在尝试查找没有“已取消”状态的计划的所有用户的 ID。很想知道是什么解释了下面的行为。

对于上下文，应该返回的是这样的：

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]

这是我得到的：

# 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]

问题：

1. 为什么语句 3 和 4 没有返回相同的结果？
2. 为什么语句 1 和 2（幸运的是它们相同并且返回相同的结果）返回的结果与语句 4 不同？对于上下文，我宁愿不在nil 上搜索，而是在"canceled" 上搜索。我可以确认所有计划的状态都是nil 或"canceled"

根据请求更新

# 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> 

Answer 1

问题 1 的答案：

您错过了在条件 sql 中，条件后面的参数被替换为 ? 而不是比较的概念。因此，将双 == 替换为 =。

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