如何避免Await.result？

Question

I have my Play app, and I want to implement kind of uniqueness validation by myself, I use Slick , so it's natural that I do a simple sum(1) where call and if that count is more than zero I set the error to my case class object . So I can't imagine the workaround to avoid Await.result on my DB query, because I need to set the error right in the current time.

But I now that Await.result is really bad practice, any suggestions ?

Answer 1

You should use map on the future:

db.run(query.result) map { response =>
  //do whatever you want with the response
}

In this case you get the response but it is not blocking as Await.result is.

Edit: so for the code you showed in your comment, it would look like:

def exists(tableName: String, column: String, value: Any): Future[Boolean] = {
  val query = dbConfig.db.run(sql"SELECT COUNT(1) from #$tableName WHERE #$column = ${value.toString};".as[Int])

  query.map(_.sum > 0)
}

Then where you need to call exists you will do

exists(...) map  { result => 
if (result == true) 
  //doSomething
}