Slick: Read nullable values as option when left join - sql

Question

Problem when using Slick to join: I have 2 tables User and UserInfo and I want to leftJoin them to get user's info. I've tried this:
val q = for{
(user,info) <- User leftJoin UserInfo on (_.id === _.userid)
} yield(user, info)
But the UserInfo table has some nullable field, so when I try to execute the query:
q.map(user_info => (user_info._1,user_info._2)).list
It makes error because user_info._2 has some null values. I know a solution that yield each field in UserInfo and add getOrElse(None) for nullable fields. However, UserInfo has many field so I don't want to use this.
Can anyone help me?

Answer 1

What you CAN do, is this define a function that does the conversion, and then use it in your map:
def nullToOption[A](input: A): Option[A] = input match {
case null => None
case x => Some(x)
}
And then you just use it in your map.
I made a simple example using a simple list:
val lst = List("Hello", null, "hi", null)
val newlst = map lst nullToOption
newList is now the following: List(Some("Hello"), None, Some("hi"), None)
Of course you can modify nullToOption to fit your needs; here's a version that takes tuples:
def nullToOption[A, B](input: (A,B)): (Option[A], Option[B]) = input match {
case (x, y) => (Some(x), Some(y))
case (x, null) => (Some(x), None)
case (null, y) => (None, Some(y))
case (null, null) => (None, None)
}