How to get scalar values from aggregate queries in 3.0

[Will Skinner]

I'm new to Slick and have have been unable to answer this seemingly simple question after reading through the 3.0.0 docs. I'm interested in counting the number of rows in a table, which in SQL would look like:

select count(*) from table;

In Slick 2 I can do something like this:

val countQuery: Column[Int] = coffees.length
val count: Int = countQuery.run

The Slick 3 docs give an example:

val q1 = coffees.length

in this case q1 has type

 Rep[Int]

and after reading through http://slick.typesafe.com/doc/3.0.0/queries.html and various other sources, I still can't figure out how to get an

Int

value from this.

[Anze Cesar]

Hi,

you get a (future of) result by executing the action, like so:

val q = coffees.length
val action = q.result
val result: Future[Int] = db.run(action)

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[Will Skinner]

Trying to do 

q.result

gives - 'cannot resolve symbol result'. Perhaps there is an implicit conversion going on from

Rep[Int]

and I need to import something?

[Anze Cesar]

Yes,
import slick.driver.PostgresDriver.api._

replace with correct driver. I think that should do it. If you're using IntelliJ Idea, it won't resolve 'result', but it compiles and works just fine.

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[Will Skinner]

Thanks! This solved the problem.