Slick MSSQL inserting object with auto increment - sql-server

Question

I've recently had to move a project over from MySQL to MSSQL. I'm using IDENTITY(1,1) on my id columns for my tables to match MySQL's auto-increment feature.
When I try to insert an object though, I'm getting this error:
[SQLServerException: Cannot insert explicit value for identity column in table 'categories' when IDENTITY_INSERT is set to OFF.]
Now after some research I found out that it's because I'm trying to insert a value for my id(0) on my tables. So for example I have an object Category
case class Category(
id: Long = 0L,
name: String
)
object Category extends Table[Category]("categories"){
def name = column[String]("name", O.NotNull)
def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
def * = id ~ name <> (Category.apply _, Category.unapply _)
def add(model:Category) = withSession{ implicit session =>
Category.insert(model)
}
def remove(id:Long) = withSession{implicit session =>
try{Some(Query(Category).filter(_.id === id).delete)}
catch{case _ => None}
}
}
Is there a way to insert my object into the database and ignoring the 0L without MSSQL throwing an SQLException? MySQL would just ignore the id's value and do the increment like it didn't receive an id.
I'd really rather not create a new case class with everything but the id.

Answer 1

Try redefining your add method like this and see if it works for you:
def add(model:Category) = withSession{ implicit session =>
Category.name.insert(model.name)
}
If you had more columns then you could have added a forInsert projection to your Category table class that specified all fields except id, but since you don't, this should work instead.
EDIT
Now if you do have more than 2 fields on your table objects, then you can do something like this, which is described in the Lifted Embedding documentation here:
case class Category(
id: Long = 0L,
name: String,
foo:String
)
object Category extends Table[Category]("categories"){
def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
def name = column[String]("name", O.NotNull)
def foo = column[String]("foo", O.NotNull)
def * = id ~ name ~ foo <> (Category.apply _, Category.unapply _)
def forInsert = name ~ foo <> (t => Category(0L, t._1, t._2), {(c:Category) => Some(c.name, c.foo)})
def add(model:Category) = withSession{ implicit session =>
Category.forInsert insert model
}
def remove(id:Long) = withSession{implicit session =>
try{Some(Query(Category).filter(_.id === id).delete)}
catch{case _ => None}
}
def withSession(f: Session => Unit){
}
}