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AASM Coder

AASM 状态机实现

State machine patterns for managing workflow states in Rails.

在Rails中管理工作流状态的状态机模式。

Setup

环境搭建

ruby

undefined

ruby

undefined

Gemfile

gem "aasm", "~> 5.5"

undefined

gem "aasm", "~> 5.5"

undefined

Basic State Machine

基础状态机

ruby

class Order < ApplicationRecord
  include AASM

  aasm column: :status do
    state :pending, initial: true
    state :paid
    state :processing
    state :shipped
    state :cancelled

    event :pay do
      transitions from: :pending, to: :paid

      after do
        OrderMailer.payment_received(self).deliver_later
      end
    end

    event :process do
      transitions from: :paid, to: :processing
    end

    event :ship do
      transitions from: :processing, to: :shipped
    end

    event :cancel do
      transitions from: [:pending, :paid], to: :cancelled

      before do
        refund_payment if paid?
      end
    end
  end
end

ruby

class Order < ApplicationRecord
  include AASM

  aasm column: :status do
    state :pending, initial: true
    state :paid
    state :processing
    state :shipped
    state :cancelled

    event :pay do
      transitions from: :pending, to: :paid

      after do
        OrderMailer.payment_received(self).deliver_later
      end
    end

    event :process do
      transitions from: :paid, to: :processing
    end

    event :ship do
      transitions from: :processing, to: :shipped
    end

    event :cancel do
      transitions from: [:pending, :paid], to: :cancelled

      before do
        refund_payment if paid?
      end
    end
  end
end

Usage

使用方法

ruby

order = Order.create!
order.pending?      # => true
order.may_pay?      # => true
order.pay!          # Transition + callbacks
order.paid?         # => true

order.may_ship?     # => false (must process first)
order.aasm.events   # => [:process, :cancel]

ruby

order = Order.create!
order.pending?      # => true
order.may_pay?      # => true
order.pay!          # Transition + callbacks
order.paid?         # => true

order.may_ship?     # => false (must process first)
order.aasm.events   # => [:process, :cancel]

Scopes created automatically

Order.pending Order.paid.where(user: current_user)

undefined

Order.pending Order.paid.where(user: current_user)

undefined

Guards

守卫机制

ruby

event :pay do
  transitions from: :pending, to: :paid, guard: :payment_valid?
end

def payment_valid?
  payment_method.present? && total > 0
end

ruby

event :pay do
  transitions from: :pending, to: :paid, guard: :payment_valid?
end

def payment_valid?
  payment_method.present? && total > 0
end

Usage

order.pay! # Raises AASM::InvalidTransition if guard fails order.pay # Returns false (no exception)

undefined

order.pay! # Raises AASM::InvalidTransition if guard fails order.pay # Returns false (no exception)

undefined

Callbacks

回调函数

ruby

aasm do
  # State callbacks
  state :paid, before_enter: :validate_payment,
               after_enter: :send_receipt

  # Event callbacks
  event :ship do
    before do
      generate_tracking_number
    end

    after do
      notify_customer
    end

    transitions from: :processing, to: :shipped
  end
end

Callback order:

```
before
```
(event)
```
before_exit
```
(old state)
```
before_enter
```
(new state)
State change persisted
```
after_exit
```
(old state)
```
after_enter
```
(new state)
```
after
```
(event)

ruby

aasm do
  # State callbacks
  state :paid, before_enter: :validate_payment,
               after_enter: :send_receipt

  # Event callbacks
  event :ship do
    before do
      generate_tracking_number
    end

    after do
      notify_customer
    end

    transitions from: :processing, to: :shipped
  end
end

回调执行顺序：

```
before
```
（事件级）
```
before_exit
```
（旧状态）
```
before_enter
```
（新状态）
持久化状态变更
```
after_exit
```
（旧状态）
```
after_enter
```
（新状态）
```
after
```
（事件级）

Multiple Transitions

多分支转换

ruby

event :approve do
  transitions from: :pending, to: :approved, guard: :auto_approvable?
  transitions from: :pending, to: :review, guard: :needs_review?
  transitions from: :pending, to: :rejected  # fallback
end

First matching guard wins.

ruby

event :approve do
  transitions from: :pending, to: :approved, guard: :auto_approvable?
  transitions from: :pending, to: :review, guard: :needs_review?
  transitions from: :pending, to: :rejected  # fallback
end

第一个匹配的守卫规则生效。

Error Handling

错误处理

ruby

undefined

ruby

undefined

Safe (returns false on failure)

order.pay # => false if invalid

Raises exception

begin order.pay! rescue AASM::InvalidTransition => e Rails.logger.error("Invalid transition: #{e.message}") end

Check before transition

if order.may_pay? order.pay! end

undefined

if order.may_pay? order.pay! end

undefined

Testing State Machines

状态机测试

ruby

RSpec.describe Order do
  let(:order) { create(:order) }

  it "starts in pending state" do
    expect(order).to be_pending
  end

  describe "pay event" do
    it "transitions to paid" do
      expect { order.pay! }
        .to change(order, :status).from("pending").to("paid")
    end

    it "sends payment received email" do
      expect(OrderMailer).to receive_message_chain(:payment_received, :deliver_later)
      order.pay!
    end
  end

  describe "ship event" do
    context "when pending" do
      it "raises error" do
        expect { order.ship! }.to raise_error(AASM::InvalidTransition)
      end
    end

    context "when processing" do
      before { order.update!(status: :processing) }

      it "transitions to shipped" do
        expect { order.ship! }
          .to change(order, :status).to("shipped")
      end
    end
  end
end

ruby

RSpec.describe Order do
  let(:order) { create(:order) }

  it "starts in pending state" do
    expect(order).to be_pending
  end

  describe "pay event" do
    it "transitions to paid" do
      expect { order.pay! }
        .to change(order, :status).from("pending").to("paid")
    end

    it "sends payment received email" do
      expect(OrderMailer).to receive_message_chain(:payment_received, :deliver_later)
      order.pay!
    end
  end

  describe "ship event" do
    context "when pending" do
      it "raises error" do
        expect { order.ship! }.to raise_error(AASM::InvalidTransition)
      end
    end

    context "when processing" do
      before { order.update!(status: :processing) }

      it "transitions to shipped" do
        expect { order.ship! }
          .to change(order, :status).to("shipped")
      end
    end
  end
end

Advanced Patterns

进阶模式

For multiple state machines, persistence options, and history tracking see:

```
references/aasm-patterns.md
```

关于多状态机、持久化选项以及历史追踪的内容，请查看：

```
references/aasm-patterns.md
```

aasm-coder

Original

Translation

AASM Coder

AASM 状态机实现

Setup

环境搭建

Gemfile

Gemfile

Basic State Machine

基础状态机

Usage

使用方法

Scopes created automatically

Scopes created automatically

Guards

守卫机制

Usage

Usage

Callbacks

回调函数

Multiple Transitions

多分支转换

Error Handling

错误处理

Safe (returns false on failure)

Safe (returns false on failure)

Raises exception

Raises exception

Check before transition

Check before transition

Testing State Machines

状态机测试

Advanced Patterns

进阶模式

Related Skills

相关技能