I have a a class like this:
case class SurveyTemplate(id:UUID,
name: String,
version: Int,
preDefinedChapter: Seq[Chapter]) {
}
I serialized this as binary in a DAO with this.
def save(input: SurveyTemplate) = Future{
val target = toFile(input)
val output = AvroOutputStream.binary[SurveyTemplate](target)
output.write(input)
output.flush()
output.close()
input
}
Now I saved the file binary to the harddisk. All fine. Now I want change the SurveyTemplate with a new field like "dummy: String"
If i now load the files and try to deserialize I get a java.util.NoSuchElementException which means their is no file which can be deserialized. If I remove the additional field all works fine.
Here is the list method:
def list(name: Option[String] = None,
version: Option[Int] = None,
authorName: Option[String] = None,
drop: Int = 0,
take: Int = 100) = Future{
storageDirectory.listFiles(new FilenameFilter {
override def accept(dir: File, name: String): Boolean = name.endsWith(ending)
}).map{e =>
println("FOUND " + e.getName)
val i = AvroInputStream.binary[SurveyTemplate](e)
println("BINARY " + i)
println(i.records.size())
println( Try(i.iterator().toSeq.head) )
val p = i.iterator().toSeq.head
i.close()
println(p)
println("------------------")
Some(p)
}.filter(_.isDefined).slice(drop,take).map(_.get)
}
How can I add the possibilty of evolution?
Thank you.
Added: Result of print´s
BINARY com.sksamuel.avro4s.AvroBinaryInputStream@58d20d47
0
Failure(java.util.NoSuchElementException: head of empty stream)
My new SurveyTemplate:
case class SurveyTemplate(id:UUID,
name: String,
version: Int,
preDefinedChapter: Seq[Chapter],
dummy: Option[String] = None) {
}
Here is now the minimal
import java.io.{File, FilenameFilter}
import java.util.UUID
import com.sksamuel.avro4s.{AvroInputStream, AvroOutputStream, AvroSchema, SchemaFor}
import scala.util.Try
object Main {
def main(args: Array[String]): Unit ={
val dao = new SurveyTemplateDAO
//RUN THIS FIRST!
val first = SurveyTemplate(UUID.randomUUID(),"TEST",0,"ICH",Seq(Chapter(1,1,"HELLO",Nil)))
dao.save(first)
//COMMENT OUT! Then uncomment the dummy in SurveyTemplate
//RUN THIS AFTER FILE SAVED
dao.list()
}
}
case class Chapter(counter: Int,
level: Int,
title: String,
subChapters: Seq[Chapter]) {
}
case class SurveyTemplate(id:UUID,
name: String,
version: Int,
authorName: String,
preDefinedChapter: Seq[Chapter]/*, dummy: Option[String] = None*/) {
}
class SurveyTemplateDAO {
private val ending = ".pst"
private val storageDirectory = new File("C:/Users/André Schmidt/Desktop/tmp")
def toFileName(x: SurveyTemplate): String = toFileName(x.id)
def toFileName(x: UUID): String = s"$x$ending"
def toFile(x: SurveyTemplate) = new File(storageDirectory.getCanonicalPath+File.separator+toFileName(x))
private implicit val schemaForChapter = SchemaFor[Chapter]
def save(input: SurveyTemplate) = {
val target = toFile(input)
val output = AvroOutputStream.binary[SurveyTemplate](target)
output.write(input)
output.flush()
output.close()
input
}
def list(name: Option[String] = None,
version: Option[Int] = None,
authorName: Option[String] = None,
drop: Int = 0,
take: Int = 100) = {
storageDirectory.listFiles(new FilenameFilter {
override def accept(dir: File, name: String): Boolean = name.endsWith(ending)
}).take(1).foreach{e =>
println("OTHER WAY")
val i = AvroInputStream.binary[SurveyTemplate](e)
println("BINARY " + i)
println(i.records.size())
//println( Try(i.iterator().toList.head) )
val p = Try(i.iterator().toList.head).toOption
i.close()
println(p)
println("OTHER WAY ------------------")
println("OTHER WAY ------------------")
println("OTHER WAY ------------------")
}
storageDirectory.listFiles(new FilenameFilter {
override def accept(dir: File, name: String): Boolean = name.endsWith(ending)
}).map{e =>
println("FOUND " + e.getName)
// val schema = SchemaBuilder.builder()
// val r = Schema.createRecord(java.util.Arrays.asList())
// val t = new AvroBinaryInputStream[SurveyTemplate](new SeekableFileInput(e),readerSchema = Some(r))
// println(t)
val i = AvroInputStream.binary[SurveyTemplate](e,AvroSchema[SurveyTemplate]/*,AvroSchema[OldSurveyTemplate]*/)
println("BINARY " + i)
println(i.records.size())
//println( Try(i.iterator().toList.head) )
val p = Try(i.iterator().toList.head).toOption
i.close()
println(p)
println("------------------")
println("ENDE")
p
// if( authorName.map(_.equalsIgnoreCase(p.authorName)).getOrElse( name.map(_.equalsIgnoreCase(p.name) ).getOrElse( version.forall(_ == p.version) ) ) ){
// Some(p)
// } else None
}.filter(_.isDefined).slice(drop,take).map(_.get)
}
}
My sbt:
name := "avroTest"
version := "0.1"
scalaVersion := "2.12.4"
libraryDependencies ++= Seq(
"com.sksamuel.avro4s" %% "avro4s-core" % "1.8.1"
)
