Scala + EclipseLink: JPA annotations treated as abstract traits, cannot be instantiated -

i writing scala backend uses eclipselink data abstraction layer.

i find having problems right out of box, although several tutorials have followed indicated no such thing. example, 1 of entities this:

@mappedsuperclass abstract class entity {    @id   @generatedvalue(strategy = generationtype.auto)   @expose   @beanproperty   protected var id: int = 0 }  @entity class user extends entity {    @expose   @temporal(temporaltype.timestamp)   @beanproperty   var createdat: date    @expose   @temporal(temporaltype.timestamp)   @beanproperty   var updatedat: date    @expose   @temporal(temporaltype.timestamp)   @beanproperty   var dateofbirth: date    @expose   @beanproperty   var twostepverificationcode: string    @expose   @beanproperty   var firstname: string    @expose   @beanproperty   var lastname: string    @expose   @beanproperty   var email: string    @expose   @beanproperty   var description: string    @expose   @beanproperty   var password: string    @expose   @beanproperty   var salt: string } 

upon compiling, however, whole set of errors related annotations:

 entity.scala:45: trait id abstract; cannot instantiated    @id     ^  entity.scala:46: trait generatedvalue abstract; cannot instantiated    @generatedvalue(strategy = generationtype.auto)     ^  user.scala:14: class entity abstract; cannot instantiated  @entity   ^  user.scala:17: trait temporal abstract; cannot instantiated    @temporal(temporaltype.timestamp)     ^  user.scala:22: trait temporal abstract; cannot instantiated    @temporal(temporaltype.timestamp)     ^  user.scala:27: trait temporal abstract; cannot instantiated    @temporal(temporaltype.timestamp)     ^ 

what missing, , how can work around it?

remember in scala field must assigned not abstract, assign fields default-value.

like this:

@column(name = "external_reference") var externalreference: option[string] = none  @manytoone(optional = false) @joincolumn(name = "account_id") @net.sf.oval.constraint.notnull var accountcode: accountcode = null 

if use jpa-2.1 have converters handy:

//// start converters option of primitive-types. /* note: not autoapply because scala generates byte-code option[java.lang.object] el isn't able apply them automatically.  */ @converter class optionlongconverter extends attributeconverter[option[long], lang.long]{      def converttodatabasecolumn(attribute: option[long]): lang.long = {         attribute.map(long2long).ornull     }      def converttoentityattribute(dbdata: lang.long): option[long] = {         if (dbdata eq null) none         else some(dbdata)     } }  @converter class optionintconverter extends attributeconverter[option[int], lang.integer]{      def converttodatabasecolumn(attribute: option[int]): lang.integer = {         attribute.map(int2integer).ornull     }      def converttoentityattribute(dbdata: lang.integer): option[int] = {         if (dbdata eq null) none         else some(dbdata)     } } 

use this:

@convert(converter = classof[optionintconverter]) var code: option[int] = none 

for reference-types converters may auto-applied:

@converter(autoapply = true) class optionbigdecimalconverter extends attributeconverter[option[bigdecimal], jbigdecimal]{      def converttodatabasecolumn(attribute: option[bigdecimal]): jbigdecimal = {         attribute.map(_.bigdecimal).ornull     }      def converttoentityattribute(dbdata: jbigdecimal): option[bigdecimal] = {         if (dbdata eq null) none         else some(dbdata)     } }  @converter(autoapply = true) class optionstringconverter extends attributeconverter[option[string], string] {      def converttodatabasecolumn(attribute: option[string]): string = {         attribute.ornull     }      def converttoentityattribute(dbdata: string): option[string] = option(dbdata) }  @converter(autoapply = true) class optiondatetimeconverter extends attributeconverter[option[datetime], timestamp] {     def converttodatabasecolumn(attribute: option[datetime]): timestamp = {         attribute.map(v => new timestamp(v.getmillis)).ornull     }      def converttoentityattribute(dbdata: timestamp): option[datetime] = {         option(dbdata).map(v => new datetime(v.gettime))     } }  @converter(autoapply = true) class optionlocaldateconverter extends attributeconverter[option[localdate], date] {     def converttodatabasecolumn(attribute: option[localdate]): date = {         attribute.map(v => new date(v.todatemidnight.getmillis)).ornull     }      def converttoentityattribute(dbdata: date): option[localdate] = {         option(dbdata).map(v => new localdate(v.gettime))     } } 

so code works, without needing specify converter on mapped-field:

@column(name = "external_reference") var externalreference: option[string] = none