Refactoring my for comprehension to remove the unsafe get calls on the option values

Question

So my for comprehension technically compiles fine currently, but if you look carefully I have a few unsafe .get calls on the options.

for {
   maybeProduct: Option[Product] <- EitherT.liftF {
        for {
           a <- ADao.get(123).transact(xa)  // ConnectionIO[Option[A]]
           b <- BDao.get(a.get).transact(xa)      // ConnectionIO[Option[B]]
           product <- CDao.get(b.get.productId.get).transact(xa) // ConnectionIO[Option[Product]]
        } yield product
  }

  transaction <- EitherT(
        TransactionDao.insert(..., maybeProduct.map(_.id),...).transact(xa)                    
   )
}

I need help refactoring it to remove the unsafe calls in the following lines in the for comprehension

           a <- ADao.get(123).transact(xa)  // ConnectionIO[Option[A]]
           b <- BDao.get(a.get).transact(xa)      // ConnectionIO[Option[B]]
           product <- CDao.get(b.get.productId.get).transact(xa) // ConnectionIO[Option[Product]]

Specifically the call to a.get and b.get.productId.get

@LuisMiguelMejíaSuárez the final return type of the EitherT is an Option[Product] so if any of the .get calls are a None, the entire thing should return None. — Blankman, Feb 24 '23 at 21:50
Then all you need to use is used `flatTraverse` and `flatMapN` — Luis Miguel Mejía Suárez, Feb 24 '23 at 21:52
@LuisMiguelMejíaSuárez Where would I use both? I am not that familiar with those but I will look them up. — Blankman, Feb 24 '23 at 21:58
Actually, looking more closely at your code, you want to use `OptionT` so you can just `flatMap` everything in the `for` — Luis Miguel Mejía Suárez, Feb 24 '23 at 22:12
@LuisMiguelMejíaSuárez if I do that, then I get an error on the `transaction <- EitherT` saying something like it requires `cats.data.EitherT[[A]cats.data.OptionT[cats.effect.IO,A],?,?]` ... — Blankman, Feb 24 '23 at 22:34
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/252118/discussion-between-blankman-and-luis-miguel-mejia-suarez). — Blankman, Feb 25 '23 at 02:21

Refactoring my for comprehension to remove the unsafe get calls on the option values

0 Answers0