Hi Timur,
Because Option[T] is not comparable type generally (if T is a POJO type), you
cannot use Option[T] as a key type. I think you have to implement KeyExtractor
to compare objects including Option[T]s.
```
case class MyKey(k1: Option[String], k2: Option[String])
val data1 = env.fromElements(MyKey(Some("a"), None), MyKey(Some("a"),
Some("c")))
val data2 = env.fromElements(MyKey(Some("b"), None), MyKey(Some("a"),
Some("c")))
data1.join(data2)
.where(_.hashCode())
.equalTo(_.hashCode()).apply {
(left: MyKey, right: MyKey) => (left, right)
}.print()
```
Note that the approach in example (using hashCode()) cannot be applied to sort
task.
Regards,
Chiwan Park
> On Mar 30, 2016, at 2:37 AM, Timur Fayruzov <[email protected]> wrote:
>
> There is some more detail to this question that I missed initially. It turns
> out that my key is a case class of a form MyKey(k1: Option[String], k2:
> Option[String]). Keys.SelectorFunctionKeys is performing a recursive check
> whether every element of the MyKey class can be a key and fails when
> encountering an Option.
>
> Is it possible to work around this situation without giving up Options?
> Inability to use Options in Domain objects could be really frustrating.
>
> Thanks,
> Timur
>
> On Tue, Mar 29, 2016 at 10:19 AM, Timur Fayruzov <[email protected]>
> wrote:
> Hello,
>
> I'm evaluating Flink and one thing I noticed is Option[A] can't be used as a
> key for coGroup (looking specifically here:
> https://github.com/apache/flink/blob/master/flink-scala/src/main/scala/org/apache/flink/api/scala/typeutils/OptionTypeInfo.scala#L39).
> I'm not clear about the reason of this and appreciate if someone can explain.
>
> Thanks,
> Timur
>
