如果可以在learning slick2之后定义嵌套类(嵌入在JPA中)像这样:
case class Person(name: Name, address: Address)
case class Name(given: String, family: String)
case class Address(street: String, city: String)
class Directory(tag: Tag) extends Table[Person](tag, "directory") {
def givenName = column["String"] ( "given_name" )
def familyName = column["String"] ( "family_name" )
def street = column["String"] ( "street" )
def city = column["String"] ( "city" )
def * = (name, address) <> (Person.tupled, Person.unapply)
def name = (givenName, familyName) <> (Name.tupled, Name.unapply)
def address = (street, city) <> (Address.tupled, Address.unapply)
}
我不想在我嵌入 Adress 的每个表中写入街道、城市和地址的定义。我想编写如下所示的内容,但是由于显而易见的原因,这不会编译,因为列是表等上的方法...是否可以以某种方式重用列定义?
object Adresses {
def street = column["String"] ( "street" )
def city = column["String"] ( "city" )
def address = (street, city) <> (Address.tupled, Address.unapply)
}
class Directory(tag: Tag) extends Table[Person](tag, "directory") {
def givenName = column["String"] ( "given_name" )
def familyName = column["String"] ( "family_name" )
def * = (name, Adresses.address) <> (Person.tupled, Person.unapply) //address from Adresses
def name = (givenName, familyName) <> (Name.tupled, Name.unapply)
}
最佳答案
您可以使 Adresses 成为从 Table 类继承的特征(是的,可行)。
trait Adresses[T] extends Table[T]{
def street = column["String"] ( "street" )
def city = column["String"] ( "city" )
def address = (street, city) <> (Address.tupled, Address.unapply)
}
class Directory(tag: Tag) extends Table[Person](tag, "directory") with Adresses[Person] {
def givenName = column["String"] ( "given_name" )
def familyName = column["String"] ( "family_name" )
def * = (name, address) <> (Person.tupled, Person.unapply) //address from Adresses
def name = (givenName, familyName) <> (Name.tupled, Name.unapply)
}
关于slick:嵌套(嵌入)类 DRY,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/23759347/