How to get optional result in insert statements with Doobie?

问题

I have an optional insert query:

val q = sql"insert into some_table (some_field) select 42 where ...(some condition)"

Running this query with:

q.update.withUniqueGeneratedKeys[Option[Long]]("id")

fails with

Result set exhausted: more rows expected

then condition is false.

How to get Optional[Long] result from insert statements with Doobie?

---

UPD

.withGeneratedKeys[Long]("id") gives just Long in for comprehension

val q = sql"insert into some_table (some_field) select 42 where ...(some condition)"
for {
  id <- q.update.withGeneratedKeys[Long]("id")   // id is long
  _ <- if (<id is present>) <some other inserts> else <nothing>
} yield id

How to check id?

回答1:

As @Thilo commented, you can use the use withGeneratedKeys which gives you back a Stream[F, Long] (where F is your effect type)

val result = q.update.withGeneratedKeys[Long]("id")

Here is the doc.

来源：https://stackoverflow.com/questions/56342218/how-to-get-optional-result-in-insert-statements-with-doobie