为具有复合主键模型的关联推断 primary_key: :id，为 enum 添加验证选项以及更多！

class Order
  self.primary_key = [:shop_id, :id]
  has_many :order_agreements, primary_key: :id
end

class OrderAgreement
  belongs_to :order, primary_key: :id
end

class Order
  self.primary_key = [:shop_id, :id]
  has_many :order_agreements
end

class OrderAgreement
  belongs_to :order
end

class Conversation < ApplicationRecord
  enum :status, %i[active archived], validate: true
end

conversation = Conversation.new
conversation.status = :unknown
conversation.valid? # => false

class Conversation < ApplicationRecord
  enum :status, %i[active archived], validate: { allow_nil: true }
end

conversation = Conversation.new
conversation.status = nil
conversation.valid? # => true

class Conversation < ApplicationRecord
  enum :status, %i[active archived]
end

conversation = Conversation.new
conversation.status = :unknown # 'unknown' is not a valid status (ArgumentError)

Post.where(id: 1...3).unscope(where: :id).to_sql # "SELECT `posts`.* FROM `posts` WHERE `posts`.`id` >= 1 AND `posts`.`id` < 3"    

Post.where(id: 1...3).unscope(where: :id).to_sql # "SELECT `posts`.* FROM `posts`"