CODEWITHSUNDEEP
javasqlscalaslickslick-3.0
S2C
S2C

Reputation: 53

How would I use slick 3.0 to return one row at a time?

How I would build a scala query to return one row of my table at a time?

My tables are in the following location if they help in answering this question: Slick 3.0 (scala) queries don't return data till they are run multiple times (I think)

 val q5 = for {
  c <- dat.patientsss 
} yield (c.PID, c.Gender, c.Age, c.Ethnicity)

Await.result((db.stream(q5.result).foreach(println)),Duration.Inf)

but instead of printing, I need return each.

Upvotes: 0

Views: 1328

Answers (1)

Roman
Roman

Reputation: 5699

Answer

Use a materialized result instead:

val result = Await.result((db.run(q5.result)), Duration.Inf)

result is a Seq that contains all your patient data. Use foreach to iterate over the result set:

result.foreach(r => yourFancyAlgorithm(r))  // r is a single patients data row

Sidenote

Await blocks the current thread making one of slick's best features obsolete. Blocking threads is something you should not do. I highly recommend to read about Future and Promise in scala.
The above example can be simply written as:

val result = db.run(q5.result))

result in this case will be of type Future[Seq[(yourPatientsData)]]. To access the data, use map on the result:

result.map(d => whatever)  // d is of type Seq[(yourPatientsData)]

While waiting for the result, the rest of your application will continue to do its calculations and stuff. Finally when the result is ready, the callback (d => whatever) will run.

Upvotes: 2

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