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Scala 有类似 AutoMapper 的东西吗？

发布于 2024-11-27 06:46:23 字数 115 浏览 3 评论 0原文

我一直在寻找一些用于映射对象到对象的 scala 流畅 API，类似于 AutoMapper。 Scala中有这样的工具吗？

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初见终念 2024-12-04 06:46:23

我认为 Scala 中不太需要像 AutoMapper 这样的东西，因为如果您使用惯用的 Scala 模型，则更容易编写和操作，并且您可以使用隐式转换轻松定义自动展平/投影。

例如，这里是 AutoMapper 的 Scala 扁平化示例中的等效项：

// The full model

case class Order( customer: Customer, items: List[OrderLineItem]=List()) {
  def addItem( product: Product, quantity: Int ) = 
    copy( items = OrderLineItem(product,quantity)::items )
  def total = items.foldLeft(0.0){ _ + _.total }
}

case class Product( name: String, price: Double )

case class OrderLineItem( product: Product, quantity: Int ) {
  def total = quantity * product.price
}

case class Customer( name: String )

case class OrderDto( customerName: String, total: Double )


// The flattening conversion

object Mappings {
  implicit def order2OrderDto( order: Order ) = 
    OrderDto( order.customer.name, order.total )
}


//A working example

import Mappings._

val customer =  Customer( "George Costanza" )
val bosco = Product( "Bosco", 4.99 )
val order = Order( customer ).addItem( bosco, 15 )

val dto: OrderDto = order // automatic conversion at compile-time !

println( dto ) // prints: OrderDto(George Costanza,74.85000000000001)

PS：我不应该使用金额翻倍...

I think there's less need of something like AutoMapper in Scala, because if you use idiomatic Scala models are easier to write and manipulate and because you can define easily automatic flattening/projection using implicit conversions.

For example here is the equivalent in Scala of AutoMapper flattening example:

// The full model

case class Order( customer: Customer, items: List[OrderLineItem]=List()) {
  def addItem( product: Product, quantity: Int ) = 
    copy( items = OrderLineItem(product,quantity)::items )
  def total = items.foldLeft(0.0){ _ + _.total }
}

case class Product( name: String, price: Double )

case class OrderLineItem( product: Product, quantity: Int ) {
  def total = quantity * product.price
}

case class Customer( name: String )

case class OrderDto( customerName: String, total: Double )


// The flattening conversion

object Mappings {
  implicit def order2OrderDto( order: Order ) = 
    OrderDto( order.customer.name, order.total )
}


//A working example

import Mappings._

val customer =  Customer( "George Costanza" )
val bosco = Product( "Bosco", 4.99 )
val order = Order( customer ).addItem( bosco, 15 )

val dto: OrderDto = order // automatic conversion at compile-time !

println( dto ) // prints: OrderDto(George Costanza,74.85000000000001)

PS: I should not use Double for money amounts...

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