Doobie. Compose .update.withGeneratedKeys() and .update.run - scala

Question

Referencing to this question.
I want to insert some entity by some condition. It can either be inserted or not. If the condition is true the entity is inserted. I want to insert some other data in various tables. It looks like this:
val q = sql"insert into some_table (some_field) select 42 where ...(some condition)"
val inserts = List(
sql"insert ...",
sql"insert ...",
sql"insert ..."
)
for {
id <- q.update.withGeneratedKeys[Long]("id")
_ <- inserts.reduce(_ ++ _).update.run
} yield id
The problem is this does not compile because the first insert is a fs2.Stream but the second one is not.
I was trying to replace _ <- inserts.reduce... with _ = inserts.reduce. The app can compile but inserts in the second line does not occur.
UPD
My possible way to solve this problem:
...
for {
idOpt <- q.update.withGeneratedKeys[Long]("id").compile.last
_ <- idOpt.fold(0.pure[ConnectionIO])(_ => inserts.reduce(_ ++ _).update.run)
} yield idOpt
This works, but IMHO this is not pretty. Is there a better way to do it?

Answer 1

One way to perform your batch inserts - if you have similar data - is to use updateMany - see doc:
import doobie._
type PersonInfo = (String, Option[Short])
def insertMany(ps: List[PersonInfo]): ConnectionIO[Int] = {
val sql = "insert into person (name, age) values (?, ?)"
Update[PersonInfo](sql).updateMany(ps)
}
// Some rows to insert
val data = List[PersonInfo](
("Frank", Some(12)),
("Daddy", None))
Also, if you remove.compile.last, you can use the fact that if your resulting Stream q.update.withGeneratedKeys[Long]("id") is empty, you 'exit early' the for-comprehension.
So all in all, here is what you could do:
import fs2.Stream
val result =
// Now the for-comprehension operates on a Stream instead of an Option
for {
r <- q.update.withGeneratedKeys[Long]("id")
_ <- Stream.eval(insertMany(data)) // insertMany(data) is defined like in the snippet above
} yield r
result.compile.last