Play 2.2 Scala class serializable for cache

Question

I have one scala class from play-mongojack example. It works fine. However, when I tried to save it in Play ehcache, it throws NotSerializableException. How can I make this class serializable?

class BlogPost(@ObjectId @Id val id: String,
             @BeanProperty @JsonProperty("date") val date: Date,
             @BeanProperty @JsonProperty("title") val title: String,
             @BeanProperty @JsonProperty("author") val author: String,
             @BeanProperty @JsonProperty("content") val content: String) {
                 @ObjectId @Id @BeanProperty var blogId: String = _
                 @BeanProperty @JsonProperty("uploadedFile") var uploadedFile: Option[(String, String, Long)] =  None
}

object BlogPost {
   def apply(
       date: Date,
       title: String,
       author: String,
       content: String): BlogPost = new BlogPost(date,title,author,content)

   def unapply(e: Event) =
       new Some((e.messageId,
          e.date,
          e.title,
          e.author,
          e.content,
          e.blogId,
          e.uploadedFile) )

    private lazy val db = MongoDB.collection("blogposts", classOf[BlogPost], classOf[String])

    def save(blogPost: BlogPost) { db.save(blogPost) }
    def findByAuthor(author: String) = db.find().is("author", author).asScala
}

Saving to cache:

var latestBlogs  = List[BlogPost]()
Cache.set("latestBlogs", latestBlogs, 30)

It throws an exception:

[error] n.s.e.s.d.DiskStorageFactory - Disk Write of latestBlogs failed:
java.io.NotSerializableException: BlogPost
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183) ~[na:1.7.0_45]
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347) ~[na:1.7.0_45]
    at java.util.ArrayList.writeObject(ArrayList.java:742) ~[na:1.7.0_45]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_45]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_45]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_45]

EDIT 1: I tried to extends the object with Serializable, it doesn't work.

object BlogPost extends Serializable {}

EDIT 2: The vitalii's comment works for me.

class BlogPost() extends scala.Serializable {}

Answer 1

Try to derive class BlogPost from Serializable or define it as a case class which are serializable by default.