CQRS阅读模型投影:数据转换有多复杂

# 命令模型中的事件
class OrderCreatedEvent:
    def __init__(self, order_id, customer_id, amount):
        self.order_id = order_id
        self.customer_id = customer_id
        self.amount = amount

# 查询模型中的投影
class CustomerProjection:
    def __init__(self):
        self.customers = {}

    def handle_order_created(self, event):
        if event.customer_id not in self.customers:
            self.customers[event.customer_id] = {'total_amount': 0, 'orders': []}
        self.customers[event.customer_id]['total_amount'] += event.amount
        self.customers[event.customer_id]['orders'].append(event.order_id)

# 事件处理器
class EventHandler:
    def __init__(self, projection):
        self.projection = projection

    def handle(self, event):
        if isinstance(event, OrderCreatedEvent):
            self.projection.handle_order_created(event)

# 示例使用
projection = CustomerProjection()
handler = EventHandler(projection)

event = OrderCreatedEvent(order_id=1, customer_id=101, amount=100)
handler.handle(event)

print(projection.customers)