Question

ActiveRecord handle timestamps doing something like this:

• Inserting data? created_at is defined
• Updating data? updated_at is redefined

How would I do it using SORM?

Answer 1

At a first glance something like this could work:

import org.joda.time._
object Db extends Instance (entities = ...) {
  override def save [T <: AnyRef : TypeTag] ( v : T ) 
    = v match {
        case v : Artist with Persisted =>
          super.save( v.copy( updatedAt = DateTime.now() ) )
        case v : Artist =>
          super.save( v.copy( createdAt = DateTime.now() ) )
        // ... so on for other entities
        case v =>
          super.save(v)
      }
}

But then how would you create those artist instances from scratch? Should those date fields be assigned with messy nulls or null-ish date values or should they maybe get wrapped in Options? Well, either of those should solve the problem, but here is another option:

import org.joda.time._
case class Artist 
  ( name : String, 
    updatedAt : DateTime = DateTime.now(),
    createdAt : DateTime = DateTime.now() )

object Db extends Instance (entities = ...) {
  override def save [T <: AnyRef : TypeTag] ( v : T ) 
    = v match {
        case v : Artist with Persisted =>
          super.save( v.copy( updatedAt = DateTime.now() ) )
        case v =>
          super.save(v)
      }
}

I gotta tell you the whole problem doesn’t feel very natural to me. I can’t imagine scenarios where that kinda behaviour would be benefitial. But then again I’ve presented you the options.