Scala 链式条件映射 - `ifDefined` 方法

Question

是否有更简洁的方法来有条件地映射值，例如：

val userName: Option[String] = Some("Bob")
val address: Option[String] = Some("Planet Earth")

val dbQuery = new Query()

val afterUserName = 
  userName.map(u => dbQuery.copy(userName = u))
    .getOrElse(dbQuery)

val modifiedQuery = 
  address.map(a => afterUserName.copy(address = a))
    .getOrElse(afterUserName)

我希望有一个 ifDefined 方法可用于所有类型，如以下块所示。这将删除 .getOrElse(...) 调用。

dbQuery
  .ifDefined(userName)((d, u) => d.copy(userName = u)
  .ifDefined(address)((d, a) => d.copy(address = a)

Answer 1

以下内容可能更短

dbQuery.copy(
  userName  = userName.getOrElse(dbQuery.userName),
  address = address.getOrElse(dbQuery.address)
)

Scala 链式条件映射 - `ifDefined` 方法

scala chained conditional mapping - `ifDefined` method

if-statement

scala

option-type