How to serialize and deserialize Java 8 dateTime in a JSON elevator?

Question

I have a case class that I want to serialize first. Then after that I want to deserialize it to save the target in MongoDB, but java 8 LocalDateTime was creating the problem. I got help at this link: how to deserialize a DateTime in an elevator but no luck. I can not write it for java 8 date time. Can someone help me with this date? Here is my code:

 import net.liftweb.json.Serialization.{read, write} implicit val formats = Serialization.formats(NoTypeHints) case class Child(var str: String, var Num: Int, var abc: Option[String], MyList: List[Int], val dateTime: LocalDateTime = LocalDateTime.now()) val ser = write(Child("Mary", 5, None, List(1, 2))) println("Child class converted to string" + ser) var obj = read[Child](ser) println("object of Child is " + obj) 

And here is the error message printed on the console:

 (run-main-0) java.lang.ArrayIndexOutOfBoundsException: 49938 java.lang.ArrayIndexOutOfBoundsException: 49938 at com.thoughtworks.paranamer.BytecodeReadingParanamer$ClassReader.<init>(BytecodeReadingParanamer.java:451) at com.thoughtworks.paranamer.BytecodeReadingParanamer$ClassReader.<init>(BytecodeReadingParanamer.java:431) at com.thoughtworks.paranamer.BytecodeReadingParanamer$ClassReader.<init>(BytecodeReadingParanamer.java:492) at com.thoughtworks.paranamer.BytecodeReadingParanamer$ClassReader.<init>(BytecodeReadingParanamer.java:337) at com.thoughtworks.paranamer.BytecodeReadingParanamer.lookupParameterNames(BytecodeReadingParanamer.java:100) at com.thoughtworks.paranamer.CachingParanamer.lookupParameterNames(CachingParanamer.java:75) at com.thoughtworks.paranamer.CachingParanamer.lookupParameterNames(CachingParanamer.java:68) at net.liftweb.json.Meta$ParanamerReader$.lookupParameterNames(Meta.scala:89) at net.liftweb.json.Meta$Reflection$.argsInfo$1(Meta.scala:237) at net.liftweb.json.Meta$Reflection$.constructorArgs(Meta.scala:253) at net.liftweb.json.Meta$Reflection$.net$liftweb$json$Meta$Reflection$$findMostComprehensive$1(Meta.scala:266) at net.liftweb.json.Meta$Reflection$$anonfun$primaryConstructorArgs$1.apply(Meta.scala:269) at net.liftweb.json.Meta$Reflection$$anonfun$primaryConstructorArgs$1.apply(Meta.scala:269) at net.liftweb.json.Meta$Memo.memoize(Meta.scala:199) at net.liftweb.json.Meta$Reflection$.primaryConstructorArgs(Meta.scala:269) at net.liftweb.json.Extraction$.decompose(Extraction.scala:88) at net.liftweb.json.Extraction$$anonfun$1.applyOrElse(Extraction.scala:91) at net.liftweb.json.Extraction$$anonfun$1.applyOrElse(Extraction.scala:89) at scala.collection.immutable.List.collect(List.scala:305) at net.liftweb.json.Extraction$.decompose(Extraction.scala:89) at net.liftweb.json.Serialization$.write(Serialization.scala:38) at TestActor$.delayedEndpoint$TestActor$1(TestActor.scala:437) at TestActor$delayedInit$body.apply(TestActor.scala:54) at scala.Function0$class.apply$mcV$sp(Function0.scala:40) at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12) at scala.App$$anonfun$main$1.apply(App.scala:76) at scala.App$$anonfun$main$1.apply(App.scala:76) at scala.collection.immutable.List.foreach(List.scala:383) at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35) at scala.App$class.main(App.scala:76) at TestActor$.main(TestActor.scala:54) at TestActor.main(TestActor.scala) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) 

If I remove the dateTime parameter from the case class, it works fine. There seems to be a problem in dateTime.

Answer 1

I ran your code in my Intellij Idea, got the same error. I tried to debug the cause, but the call stack is so deep that I finally gave up. But perhaps this is because Lift does not provide a default format for LocaleDateTime, like the message mentioned, "this is the DateParser format that uses the default by default."

Here is a compromise for your reference, Lift-JSON provides a default date format for us

 // net.liftweb.json.Serialization Line 72 def formats(hints: TypeHints) = new Formats { val dateFormat = DefaultFormats.lossless.dateFormat override val typeHints = hints } 

Therefore, instead of completely writing a custom serializer, we can also change our data type to fit the default date format. In addition, net.liftweb.mongodb.DateSerializer (line 79) provides date serialization support.

Then we can provide a method to easily get LocaleDateTime. This is how I try to figure it out.

 package jacoffee.scalabasic import java.time.{ ZoneId, LocalDateTime } import java.util.Date // package object defined is for Scala compiler to look for implicit conversion for case class parameter date package object stackoverflow { implicit def toDate(ldt: LocalDateTime): Date = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant()) implicit def toLDT(date: Date): LocalDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault()) } package jacoffee.scalabasic.stackoverflow import java.time.LocalDateTime import java.util.Date import net.liftweb.json.{ NoTypeHints, Serialization } import net.liftweb.json.Serialization.{ read, write } case class Child(var str: String, var Num: Int, var abc: Option[String], myList: List[Int], val date : Date = LocalDateTime.now()) { def getLDT: LocalDateTime = date } object DateTimeSerialization extends App { implicit val formats = Serialization.formats(NoTypeHints) val ser = write(Child("Mary", 5, None, List(1, 2))) // Child class converted to string {"str":"Mary","Num":5,"myList":[1,2],"date":"2015-07-21T03:07:05.699Z"} println(" Child class converted to string " + ser) var obj=read[Child](ser) // Object of Child is Child(Mary,5,None,List(1, 2),Tue Jul 21 11:48:22 CST 2015) println(" Object of Child is "+ obj) // LocalDateTime of Child is 2015-07-21T11:48:22.075 println(" LocalDateTime of Child is "+ obj.getLDT) } 

Anyway, hope this helps.