json - Scala Play 2.4 Serialize with Parameter Type -

i took at: scala type deferring, looks close problem can't resolve answer, unfortunately.

so, here's code:

my genericmodel

abstract class genericmodel[t] {   val _id: option[bsonobjectid]   def withid(newid: bsonobjectid): t } 

my implemented model

case class push (_id: option[bsonobjectid], text: string) extends genericmodel[push] {   override def withid(newid: bsonobjectid) = this.copy(_id = some(newid)) }  object push{   implicit val pushformat = json.format[push] } 

my dao, using case class

trait genericdao[t <: genericmodel[t]] {    val db: db   val collectionname: string    /**    * inserts new object    * @param newobject    * @return some(stringified bsonid) or none if error    */   def insert(newobject: t)(implicit tjs: writes[t]): future[option[bsonobjectid]] = {     val bsonid = bsonobjectid.generate     val beaconwithid = newobject.withid(bsonid)     db.collection[jsoncollection](collectionname).insert(beaconwithid).map{ lasterror =>       if(lasterror.ok)         some(bsonid)       else         none     }   } } 

i got error

no json serializer jsobject found type t. try implement implicit owrites or oformat type 

here, during insert method

db.collection[jsoncollection](collectionname).insert(beaconwithid) 

like said before, tried implicit writes. help, hope didn't missed on referenced topic on beggining.

the idea add [t : writes], question where. can try :

trait genericdao[t <: genericmodel[t]] {    val db: db   val collectionname: string    /**    * inserts new object    * @param newobject    * @return some(stringified bsonid) or none if error    */   def insert[t : writes](newobject: t)(implicit tjs: writes[t]): future[option[bsonobjectid]] = {     val bsonid = bsonobjectid.generate     val beaconwithid = newobject.withid(bsonid)     db.collection[jsoncollection](collectionname).insert(beaconwithid).map{ lasterror =>       if(lasterror.ok)         some(bsonid)       else         none     }   } } 

or perhaps (or both) :

abstract class genericmodel[t : writes] {   val _id: option[bsonobjectid]   def withid(newid: bsonobjectid): t }