在Rails中实现租赁商店:如何随时间跟踪库存状态?

我会使用一对插件来完成这项工作。这将使用四种型号。滑雪板、商店、用户和审计。

acts_as_state_machine acts_as_audited

AASM简化了状态转换。而审核会创建所需的历史记录。

Store和User的代码很简单,它将处理审计模型。

class Snowboard < ActiveRecord::Base

  include AASM
  belongs_to :store
  

  aasm_initial_state :unread
  acts_as_audited :only => :state

  aasm_state :maintenance
  aasm_state :available
  aasm_state :rented

  aasm_event :send_for_repairs do
    transitions :to => :maintenance, :from => [:available]
  end

  aasm_event :return_from_repairs do
    transitions :to => :available, :from => [:maintenance]
  end

  aasm_event :rent_to_customer do
   transitions :to => :rented, :from => [:available]
  end

  aasm_event :returned_by_customer do
    transitions :to => :available, :from => [:rented]
  end
end

class User < ActiveRecord::Base
  has_many :full_history, :class_name => 'Audit', :as => :user,
   :conditions => {:auditable_type => "Snowboard"}
end    

假设您的客户是控制器操作期间的当前用户,当状态发生变化时,这就是您所需要的。

@snowboard.audits

要获取客户的租赁历史记录,请执行以下操作:

@customer.full_history

您可能希望创建一个助手方法,将客户的历史记录塑造成更有用的内容。也许有点像他的:

 def rental_history
    history = []
    outstanding_rentals = {}
    full_history.each do |item|
      id = item.auditable_id
      if rented_at = outstanding_rentals.keys.delete(id)
        history << { 
          :snowboard_id => id, 
          :rental_start => rented_at,
          :rental_end => item.created_at
        }   
      else
        outstanding_rentals[:id] = item.created_at
      end
    end
    history << oustanding_rentals.collect{|key, value| {:snowboard_id => key,  
      :rental_start => value}
  end
end

script/generate model Snowboard name:string price:integer ...
script/generate model Customer name:string ...
script/generate model Store name:string ...

id created_at , modified_at (日期)

相反,我会创建滑雪板活动模型(你可以称之为 SnowboardHistory

• ev_type (即0表示归还,1表示维护,2表示租赁…)
• snowboard_id (非空)
• customer_id
• store_id

例如

script/generate model SnowboardEvent ev_type:integer snowboard_id:integer \
    customer_id:integer store_id:integer

然后我就把所有的关系 SnowboardEvent , Snowboard Customer 和 Store . 滑雪板可以有如下功能 current_state current_store 实施为

class Snowboard < ActiveRecord::Base
  has_many :snowboard_events
  validates_presence_of :name

  def initialize(store)
    ev = SnowboardEvent.new(
         {:ev_type => RETURN,
          :store_id => store.id,
          :snowboard_id = id,
          :customer_id => nil})
    ev.save
  end

  def current_state
    ev = snowboard_events.last
    ev.ev_type          
  end

  def current_store
    ev = snowboard_events.last
    if ev.ev_type == RETURN
      return ev.store_id
    end
    nil
  end

  def rent(customer)
    last = snowboard_events.last
    if last.ev_type == RETURN
      ev = SnowboardEvent.new(
           {:ev_type => RENT,
            :snowboard_id => id,
            :customer_id => customer.id
            :store_id => nil })
      ev.save
    end
  end

  def return_to(store)
    last = snowboard_events.last
    if last.ev_type != RETURN
      # Force customer to be same as last one
      ev = SnowboardEvent.new(
           {:ev_type => RETURN,
            :snowboard_id => id,
            :customer_id => last.customer.id
            :store_id => store.id})
      ev.save
    end
  end
end

顾客也会有同样的感受 has_many :snowboard_events .

检查滑雪板或客户历史记录,只需使用 Snowboard.snowboard_events 或 Customer.snowboard_events 创建于 这些事件的性质。我不认为使用Observer是必要的或相关的。

注意:上面的代码没有经过测试,也不是完美的,只是为了得到这个想法:)