Scala选项映射到另一个选项

本文介绍了Scala选项映射到另一个选项的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

从选项映射时，有没有一种方法可以避免将可能为空的结果包装在另一个选项内.

Is there a way to avoid having to wrap a potentially null result inside another option when mapping from an option.

option.flatMap(arg => Option(arg.somePotentiallyNullValue))

例如类似

option.optionMap(arg => arg.somePotentiallyNullValue )

我的代码库中只有很多Java代码，这意味着将地图结果永久包装在其他Option调用中.

I just have a lot of Java code in our codebase that means forever wrapping the results of maps in further Option calls.

推荐答案

从可为空的类型到Option的隐式转换又如何呢?在范围内的某个地方声明这一点:

What about implicit conversion from nullable type to Option? Declare this somewhere in scope:

implicit def toOption[T](x: T) : Option[T] = Option(x)

稍后编译器会解决这个问题:

Later the compiler will figure it out:

option.flatMap(_.somePotentiallyNullValue)

由于flatMap期望Option[T]作为结果值，因此编译器使用toOption隐式转换，如下所示:

Since flatMap expects Option[T] as a result value, compiler uses toOption implicit conversion like this:

option.flatMap(arg => toOption(arg.somePotentiallyNullValue))