[Gem] AASM 狀態機

# AASM is a continuation of the acts-as-state-machine rails plugin, built for plain Ruby objects.
gem 'aasm', '~> 4.12', '>= 4.12.0'

##
# check status
##

job.running?           # => true
job.may_run?           # => false

job.aasm.current_state # stage3
job.aasm_state         # => 'sleeping'
job.aasm.human_state   # => 'sleeping'
job.aasm.states(:permitted => true).map(&:name)   # show all permitted states (from initial state)
job.aasm.states(:permitted => false).map(&:name)  # show all non permitted states
job.aasm.events.map(&:name)                       # show all possible (triggerable) events from the current state

##
# change status 的方法要根據在 AASM 中 event 所定義的名稱
##
job.sleep  # => triggered :sleep
job.sleep! # => triggered :sleep!

Job.aasm.states_for_select  # 產生可以直接套用到 select 的 options

# 假設 Order 有 paid 的狀態，那麼可以直接使用
Order.paid

# ./OnePageShop/app/models/order.rb
class Order < ApplicationRecord
  # Concerns macros
  include AASM

  # Attributes related macros
  aasm column: 'status', no_direct_assignment: true, requires_lock: true do
    # 等待付款
    state :waiting_for_payment, initial: true
    # 已付款
    state :paid
    # 已出貨
    state :shipped
    # 訂單逾期
    state :expired
    # 已退款
    state :refunded

    after_all_transitions :generate_status_transition_log!

    event :mark_as_paid do
      transitions from: %i(placed waiting_for_payment), to: :paid
    end

    event :mark_as_shipped do
      transitions from: :paid, to: :shipped
    end

    event :mark_as_expired do
      transitions from: :waiting_for_payment, to: :expired
    end

    event :mark_as_refunded do
      transitions from: :paid, to: :refunded
    大专栏  [Gem] AASM 狀態機n class="keyword">end
  end

  # ...

  private
    # callback methods
    def can_not_be_destroyed
      throw :abort
    end

    def generate_status_transition_log!
      status_logs.create!(status: aasm.to_state)
    end
end

# ./OnePageShop/app/models/transaction.rb
class Transaction < ApplicationRecord
  # Concerns macros
  include AASM

  # Attributes related macros
  aasm column: 'status', no_direct_assignment: true, requires_lock: true do
    # 等待繳款
    state :waiting_for_payment, initial: true
    # 已付款
    state :paid
    # 交易失敗
    state :failed
    # 取消
    state :canceled
    # 逾期
    state :expired
    # 已退款
    state :refunded

    after_all_transitions :generate_status_transition_log!

    event :mark_as_paid do
      transitions from: :waiting_for_payment, to: :paid
    end

    event :mark_as_paid do
      transitions from: :waiting_for_payment, to: :failed
    end

    event :mark_as_canceled do
      transitions from: :waiting_for_payment, to: :canceled
    end

    event :mark_as_expired do
      transitions from: :waiting_for_payment, to: :expired
    end

    event :mark_as_refunded, after: :check_all_transactions_refunded! do
      transitions from: :paid, to: :refunded
    end
  end

  # callbacks
  after_initialize :generate_trade_number
  after_create :generate_status_change_log!
  after_update :update_order_status!

  private
    # callback methods
    def generate_status_change_log!
      status_logs.create!(status: aasm.current_state)
    end

    def generate_status_transition_log!
      status_logs.create!(status: aasm.to_state)
    end

    def update_order_status!
      return if payment_info.nil?

      if self.paid?
        # set all waiting for payment transaction as canceled
        self.order.transactions.waiting_for_payment.each do |transaction|
          transaction.mark_as_canceled! if transaction.may_mark_as_canceled?
        end

        self.order.mark_as_paid! if self.order.may_mark_as_paid?
      end
    end

    def check_all_transactions_refunded!
      # 若沒有其餘等待付款或已付款的交易，則將訂單狀態改為已退款
      if !Transaction.where(order_id: self.order_id, status: %i(waiting_for_payment paid)).exists?
        self.order.mark_as_refunded!
      end
    end
end