CODEWITHSUNDEEP
scalaslick-3.0frm
initmax
initmax

Reputation: 395

slick 3 mapping custom fields

I have case class with a lot of fields 

 case class H(     
                           id: Int, 
                           min: Option[String] = None,
                           max: Option[String] = None,
                           step: Option[String] = None,
                           ...
                           )

How can I map a few field to the table? 

class TH(tag: Tag) extends Table[H](tag, "H") {
  def id = column[Long]("ID", O.PrimaryKey, O.AutoInc)
  def min = column[Option[String]]("M")

  def * = (id, min) <>(H.tupled, H.unapply)
}

when I tried like this - def * = (id, min) <>(H.tupled, H.unapply) , instead of map all fields, got compilation exception. Can I map custom field to the table ?

BR!

Upvotes: 1

Views: 1799

Answers (1)

Julien Lafont
Julien Lafont

Reputation: 7877

tupled and unapply are just basics function generated by the case class which define the following functions (among other things) with all the fields of the case class.

For example, for a case class X(a: A, b: B, c: C, d: D), you have:

def tupled(a: a, b: b, c: c, d: d): X
def unapply(x: X): Option[(A, B, C, D)]

In other hand, your projection constructed with <> expects parameters: (f: (U => R), g: (R => Option[U])), where U is the combinaison of your fields type.

You're not tied to use the "automatic" tupled/unapply if they don't match your needs, you can provides your own definition:

class TH(tag: Tag) extends Table[H](tag, "H") {
  def id = column[Long]("ID", O.PrimaryKey, O.AutoInc)
  def min = column[Option[String]]("M")

  def * = (id, min) <> (
    { tuple: (Long, Option[String]) => TH(id, min) },
    { th: TH => Some((th.id, th.min)) }
  )
}

Upvotes: 2

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