Scala & Play! & Slick & PostgreSQL auto increment

问题

I have the following code in Scala:

case class Product(id: Option[Long] = None, name: String, price: BigDecimal, description: String)

object Products extends Table[Product]("product") {
  def id = column[Long]("id", O.AutoInc, O.PrimaryKey)
  def name = column[String]("name", O.NotNull)
  def price = column[BigDecimal]("price", O.NotNull)
  def description = column[String]("description", O.NotNull)

  def * = id.? ~ name ~ price ~ description <>(Product.apply _, Product.unapply _)

  def autoInc = * returning id

  def add(product: Product)(implicit s:Session): Long = {
    Products.autoInc.insert(product)
  }

  def all(implicit s:Session): List[Product] = {
    Query(Products).list
  }
}

Listing all products works great, however, I can't make adding method working.

After calling:

val myProduct = models.Product(id = None, name = "test2", price = BigDecimal(2.99), description = "test3")
models.Products.add(myProduct)

I constanty get an error message from PostgreSQL saying that id cannot be null. I totally agree with that, but why the id column is not being set by autoInc? Doesn't it work that way?

I use Play! 2.1.2, Scala 2.10.0, PostgreSQL 9.3 and play-slick 0.3.3.

Thanks in advance.

回答1:

Here is a suggestion, rewrite your autoInc and add methods like this:

def autoInc = name ~ price ~ description returning id

def add(product: Product)(implicit s:Session): Long = {
    Products.autoInc.insert(p.name, p.price, p.description)
}

Some databases own't allow you to insert null in the auto increment column. Maybe it's the Postgres case.

来源：https://stackoverflow.com/questions/17634152/scala-play-slick-postgresql-auto-increment