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https://issues.apache.org/jira/browse/SPARK-19492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15855971#comment-15855971
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Loic Descotte edited comment on SPARK-19492 at 2/7/17 1:24 PM:
---------------------------------------------------------------
[~sowen]
I'm compiling my project with sbt, not in a shell.
It's a compilation error, it seems to occur when type cannot be found from the
context. I.E. the compiler can't be sure the parameter will always be a
Department. The exact same thing is working with Scala Seq :
{code}
val departments = Seq(
Department(1, "hr"),
Department(2, "it")
)
departments.filter{ case Department(_, name)=>
name == "hr"
} // working
{code}
So I guess there is something wrong is the way the filter method of dataset
determines the type of the dataset elements?
I'll check in a shell and I'll tell you
was (Author: loicd):
[~sowen] It's a compilation error, it seems to occur when type cannot be found
from the context. I.E. the compiler can't be sure the parameter will always be
a Department. The exact same thing is working with Scala Seq :
{code}
val departments = Seq(
Department(1, "hr"),
Department(2, "it")
)
departments.filter{ case Department(_, name)=>
name == "hr"
} // working
{code}
So I guess there is something wrong is the way the filter method of dataset
determines the type of the dataset elements?
I'll check in a shell and I'll tell you
> Dataset, map, filter and pattern matching on elements
> -----------------------------------------------------
>
> Key: SPARK-19492
> URL: https://issues.apache.org/jira/browse/SPARK-19492
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.0.2, 2.1.0
> Reporter: Loic Descotte
>
> It seems it is impossible to use pattern matching to define input parameters
> for functions like filter, map, etc. on datasets.
> Example :
> This one is working :
> {code}
> val departments = Seq(
> Department(1, "hr"),
> Department(2, "it")
> ).toDS
> departments.filter{ d=>
> d.name == "hr"
> }
> {code}
> but not this one :
> {code}
> departments.filter{ case Department(_, name)=>
> name == "hr"
> }
> {code}
> Error :
> {code}
> error: missing parameter type for expanded function
> The argument types of an anonymous function must be fully known. (SLS 8.5)
> Expected type was: ?
> departments.filter{ case Department(_, name)=>
> {code}
> This kind of pattern matching should work (as departements dataset type is
> known) like Scala collections filter function, or RDD filter function for
> example.
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