Can deserialize avros to Scala case-classes from in-memory, but why not from files? Record can't be cast to case class?

Question

I'm trying to use Salat-Avro to serialize and deserialize Scala case classes.

I can serialize and deserialize fine in memory, but I can only serialize to files; I can't deserialize form file yet.

Why won't my DatumReader succeed when reading from a file like it did when reading from a stream?

[error] (run-main) java.lang.ExceptionInInitializerError
java.lang.ExceptionInInitializerError
at Main.main(salat-avro-example.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
Caused by: java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot be cast to models.Record
at Main$.<init>(salat-avro-example.scala:55)
at Main$.<clinit>(salat-avro-example.scala)
at Main.main(salat-avro-example.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
java.lang.RuntimeException: Nonzero exit code: 1
at scala.sys.package$.error(package.scala:27)
[error] {file:/home/julianpeeters/salat-avro-example/}default-7321ab/compile:run: Nonzero exit code: 1
[error] Total time: 18 s, completed Aug 30, 2012 12:04:01 AM

Here's the code:

val obj2 = grater[Record].asObjectFromDataFile(infile)

calls:

lazy val asDatumReader: AvroDatumReader[X] = asGenericDatumReader
lazy val asGenericDatumReader: AvroGenericDatumReader[X] = new AvroGenericDatumReader[X](asAvroSchema)def asObjectFromDataFile(infile: File): X = {
val asDataFileReader: DataFileReader[X] = new DataFileReader[X](infile, asDatumReader)
asDataFileReader.next()

} `

The code can also be seen at Github.com: Salat-Avro-Example.scala and Salat-Avro.avrograter.scala

How do I fix this? Thanks!

Answer 1

Now I see that dataFileReader.next returned a record, but the values of the fields were still UTF-8, and I needed to unmarshall the values back into a scala object with applyValues. Something like the hackish thing below worked for me:

 val objIterator = asDataFileReader.asScala
                                  .iterator
                                  .map(i => asGenericDatumReader.applyValues(i.asInstanceOf[GenericData.Record]).asInstanceOf[X])