changed 2 years ago  
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Domain-Driven Design

Domain Model ~= Businss Model aka Business Logic

Type State Method
Entity/Aggregate/Value Yes Yes
Service No Yes
  • Aggregate -> ID (Unique)
    • Boundary ~= Module -(組成)–> System
    • Aggreate ~= Moudle ===> 找 Aggregate Root == 找邊界
    • State
      • Order -> sub-total …
      • OrderItems -> [OrderItem<id: 1>]
    • Method
      • Change State
      • Change Aggregated Entity State -> order.update_amount(product_id, amount)
        • items.select { |i| i.pid == product_id }.update_amount(amount)
    • When Save, all aggregate entities are saved
      • has_many :items autosave: true
  • Entity -> ID (Unique)
    • State
      • OrderItem -> unit_price …
    • Method
      • update_amount() => self.amount = amount
  • Value Object -> No ID -> Not Unique
    • Immutable
    • Money -> Composite([100, TWD])
  • Service Object
    • Order 想 update_amount 時，商品數量必須足夠 <== 條件
    • OrderItemAmountUpdater ->
      • Service 協調
      • prodsuct.stock_available?(amount)
      • order.update_amount(product.id, amount)































# Product (Context)
# * Context - Store Manager
# * Context - Customer

class Money
    attr_reader :value, :currency
    
    def initialize(value, currency)
        @value = value
        @currency = currency
    end
    
    def +(other)
        # check currency
        new(value + other.value, currency)
    end
end

module Store
   class Product
       belongs_to :store
       compose_of :price, class_name: 'Money', mapping: [%i(price value), %i(currency currency)]
   end
end

class Order
    # ---> product.xxxx
    # product_id (Value != Association) --> Link
    # product_name
    # product_unit_price
end

Flow

-> View
-> Controller – User Flow
-> A Case -> Reseller -> No stock check
-> B Case -> Customer -> Check stock
-> Model – Business Logic


















































class CheckoutController
    def create
        # Step 1
        cart.items.each do |item|
            # ... check
            item.product_id
        end
        
        # Step 2
        Order.create_from(cart)
        
        # 拆 Service Object
    end
end

# ...
class CheckoutController
    rescue_from ...., :on_product_not_available
    # ....
    
    def create
        # Step 1
        ProductAvailableService.new.call(cart)
        # raise Error
       
        
        # Step 2
       @order = BuildOrderService.new.call(cart)
        @order.save!
        # render
    end
end

class Reseller::CheckoutController
    rescue_from ...., :on_product_not_available
    # ....
    
    def create
        # Step 1
        # ProductAvailableService.new.call(cart)
        # raise Error
       
        
        # Step 2
       @order = BuildOrderService.new.call(cart)
        @order.save!
        # render
    end
end
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