[Rails]AASM套件教學

發表於 更新於 分類於 ，

參考文件：

官方文件
為你自己學

教學開始

在自己的model引入AASM

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class Job
  include AASM

  aasm do
    state :sleeping, :initial => true
    state :running, :cleaning

    event :run do
      transitions :from => :sleeping, :to => :running
    end

    event :clean do
      transitions :from => :running, :to => :cleaning
    end

    event :sleep do
      transitions :from => [:running, :cleaning], :to => :sleeping
    end
  end

end

state統整所有可能的狀態-initial為初始狀態
event各個事件method名稱
transitions從(from)什麼狀態改為(to)什麼狀態

此時我們在rails console也有了下面的methods可以呼叫

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job = Job.new
job.sleeping? # => true
job.may_run?  # => true
job.run
job.running?  # => true
job.sleeping? # => false
job.may_run?  # => false
job.run       # => raises AASM::InvalidTransition

這時候在controller裡面可以呼叫

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…
    @job.run!
...

執行結果:
job.aasm_state從原本的"sleeping"更新為"running"

注意:
1.transitions from可以是一個陣列，但如果呼叫了此event但值不包含在from裡面則會報錯！
ex:
在job.aasm_state還是sleeping的時候執行@job.clean!

2.aasm do預設執會去找aasm_state這個欄位，如要設定哪個欄位請使用aasm(xxx) do
ex:
想要他去偵測一個location欄位需要寫成aasm(:location) do

3.我們可以宣告多個欄位，但有重複的event後面的會覆蓋到前面的event，請善用namespace！
ex:

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class NamespacedMultipleExample
  include AASM
  aasm(:status) do
    state :unapproved, :initial => true
    state :approved

    event :approve do
      transitions :from => :unapproved, :to => :approved
    end

    event :unapprove do
      transitions :from => :approved, :to => :unapproved
    end
  end

  aasm(:review_status, namespace: :review) do
    state :unapproved, :initial => true
    state :approved

    event :approve do
      transitions :from => :unapproved, :to => :approved
    end

    event :unapprove do
      transitions :from => :approved, :to => :unapproved
    end
  end
end

在rails console呼叫:

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namespaced = NamespacedMultipleExample.new

namespaced.aasm(:status).current_state
# => :unapproved
namespaced.aasm(:review_status).current_state
# => :unapproved
namespaced.approve_review
namespaced.aasm(:review_status).current_state
# => :approved

以上我認為已經很夠用，如果想了解更多再去翻文件吧！
官方文件