Rails 在多态中使用状态机

Question

我有这个多态模型。

class Note < ApplicationRecord

  belongs_to :notable, polymorphic: true, optional: false


  state_machine :is_status, initial: :pending do
    transition pending: :approved, on: %i[approve]
    transition pending: :cancelled, on: %i[cancel]
  end
end

和其他两个模型

class Invoice < ApplicationRecord

  has_many :notes, as: :notable, dependent: :destroy
end

class Person < ApplicationRecord

  has_many :notes, as: :notable, dependent: :destroy
end

如您所见，我在两个模型中附加了个人或发票的注释。并且还使用状态机。场景是我只想在invoice 中使用状态机？这可能吗。 所以。如果我的 notable_type 是“发票”。我的状态是“待定”，否则我的状态是 Person：nil

Answer 1

我建议您创建一个封装状态机行为的新模型，然后将该模型附加到发票上。

如果状态机旨在表示 Invoice 的状态，则将其设置为 InvoiceState belongs_to Invoice 和 Invoice has_one InvoiceState。

另一方面，如果您想使用此状态机来表示更一般的完整性概念，则将其命名为适当的通用名称（TransactionState 等）并通过多态关系附加它，例如 Note。

我描述的可能是这样的：

class Note < ApplicationRecord
  belongs_to :notable, polymorphic: true, optional: false
end

class Person < ApplicationRecord    
  has_many :notes, as: :notable, dependent: :destroy
end

class Invoice < ApplicationRecord    
  has_many :notes, as: :notable, dependent: :destroy
  has_one :invoice_state, dependent: :destroy
end

class InvoiceState < ApplicationRecord
  belongs_to :invoice, optional: false

  state_machine :status, initial: :pending do
    transition pending: :approved, on: %i[approve]
    transition pending: :cancelled, on: %i[cancel]
  end
end

Answer 2

如我所见，您可以将notable_type == Invoice 传递给状态机以过滤其他 notable_types 的条件

Answer 3

您可以参考 AASM gem。 https://github.com/aasm/aasm .这不仅可以帮助您在所有转换中添加保护方法，还可以在回调之前和之后。

您还可以添加 AASM 挂钩方法并在那里设置状态。例如：-

class Note < ApplicationRecord
  belongs_to :notable, polymorphic: true, optional: false
  include AASM
  aasm do
    state :pending
    state :approved
    state :cancelled
    event :approve do
      transitions from: :pending, to: :approved, before: some_method, after: some_method1
    end
    event :cancel do
      transitions from: :pending, to: :cancelled, before: some_method2, after: some_method3
    end
  end
    def aasm_ensure_initial_state
      if notable_type == "Invoice"
        self.aasm_state = :pending
      else
        self.aasm_state = nil
      end
    end
    def some_method
        puts "Some actions can be taken here."
    end
  end
end