Slick 3.0.0 Select and Create or Update - scala

Question

I'am in a situation where in I have to do a select first, use the value to issue a create. It is some versioning that I'm trying to implement. Here is the table definition:
class Table1(tag: Tag) extends Table[(Int, String, Int)](tag, "TABLE1") {
def id = column[Int]("ID")
def name = column[String]("NAME")
def version = column[Int]("VERSION")
def indexCol = index("_a", (id, version))
val tbl1Elems = TableQuery[Table1]
}
So when a request comes to create or update an entry in Table1, I have to do the following:
1. Select for the given id, if exists, get the version
2. Increment the version
3. Create a new entry
All that should happen in a single transaction. Here is what I have got so far:
// this entry should be first checked if the id exists and if yes get //the complete set of columns by applying a filter that returns the max //version
val table1 = Table1(2, "some name", 1)
for {
tbl1: Table1 <- tbl1MaxVersionFilter(table1.id)
maxVersion: Column[Int] = tbl1.version
result <- tbl1Elems += table1.copy(version = maxVersion + 1) // can't use this!!!
} yield result
I will later wrap that entire block in one transaction. But I',m wondering how to complete that will create a new version? How can I get the value maxVersion out of the Column so that I can increment 1 to it and use it?

Answer 1

I would go with a static query, with something like this
import scala.slick.jdbc.{StaticQuery=>Q}
def insertWithVersion(id: Int,name:String) =
( Q.u + "insert into table1 select " +?id + "," +?name + ", (
select coalese(max(version),1) from table1 where id=" +?id +")" ).execute
If you want to write it using slick way then take a look at the following
val tableOne = TableQuery[Table1]
def updateWithVersion(newId:Int,name:String):Unit = {
val version = tableOne.filter( _.id === newId).map( _.version).max.run.getOrElse(1)
tableOne += (newId,name,version)
}
The idea is select the max version in the same query and if there is no version use 1 and insert it. Also, as the whole logic is issued in a single statement, no extra transaction management is needed.
P.S. There might be some error is sql and code.