GitHub user drewrobb opened a pull request:
https://github.com/apache/spark/pull/18766
[SPARK-8288][SQL] ScalaReflection can use companion object constructor
## What changes were proposed in this pull request?
This change fixes a particular scenario where default spark SQL can't
encode types that are generated by twitter scrooge. In particular, these types
have the pattern of being a trait with a constructor defined only in a
companion object, rather than a case class. The situation is described in the
original issue in more detail. In this case, the type has no corresponding
constructor symbol and causes an exception. This change catches the case where
the type has no constructor and looks for an `apply` method on the type's
companion object. There might be situations in which this approach would also
fail in a new way, but it does work for the specific scrooge example,.
## How was this patch tested?
I've added a single new test that failed prior to my fix. The failure is
shown below. The test includes an example type that resembles what scrooge
generates. For an full scrooge example, see
https://gist.github.com/anonymous/ba13d4b612396ca72725eaa989900314
```
[info] - SPARK-8288 *** FAILED *** (7 milliseconds)
[info] scala.ScalaReflectionException: <none> is not a term
[info] at
scala.reflect.api.Symbols$SymbolApi$class.asTerm(Symbols.scala:199)
[info] at
scala.reflect.internal.Symbols$SymbolContextApiImpl.asTerm(Symbols.scala:84)
[info] at
org.apache.spark.sql.catalyst.ScalaReflection$class.constructParams(ScalaReflection.scala:872)
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/drewrobb/spark SPARK-8288
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18766.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #18766
----
commit f1cda4c0556319d829730f709f45104419b7b692
Author: Drew Robb <[email protected]>
Date: 2017-07-29T01:45:00Z
ScalaReflection can use companion object constructor
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