adamw

def insertPerson(p: Person): ConnectionIO[Int] = 
  sql"INSERT INTO persons(name, age) VALUES(${p.name}, ${p.age})".update.run
def countPersons: ConnectionIO[Int] = 
  sql"SELECT COUNT(*) FROM persons".query[Int].unique

val insertAndCount = 
  insertPerson(Person("Pedro", 81)).flatMap(_ => countPersons)

adamw

val transactor: Transactor[IO] = ???
val result: IO[List[Person]] = personsQuery.transact(transactor)

val persons: List[Person] = result.unsafeRunSync()

adamw

// details on creating a transactor are omitted
val transactor: Transactor[IO] = ???
 
val result: IO[List[Person]] = personsQuery.transact(transactor)

adamw

import doobie._
import doobie.implicits._

case class Person(name: String, age: Int)
val personsQuery: ConnectionIO[List[Person]] = 
  sql"SELECT p.name, p.age FROM persons p".query[Person].to[List]

adamw

Functional Scala CRUD

We'll be adding a feature to Bootzooka, a skeleton Scala microservice/web application project.

This will involve using doobie, monix, tapir, http4s, circe and compile-time dependency injection.

If you'd like to follow along:

1. make sure you have Java & sbt installed. You can use sdkman for Java and popular package manages for sbt (e.g. brew)
2. git clone https://github.com/softwaremill/bootzooka.git

adamw

val TestConfig: Config = DefaultConfig
  .modify(_.email.emailSendInterval)
  .setTo(100.milliseconds)

adamw

def changePassword(userId: Id @@ User, 
                     currentPassword: String, 
                     newPassword: String): ConnectionIO[Unit] =
    for {
      user <- userOrNotFound(UserModel.findById(userId))
      _ <- verifyPassword(user, currentPassword)
      _ = logger.debug(s"Changing password for user: $userId")
      _ <- UserModel.updatePassword(userId, User.hashPassword(newPassword))
    } yield ()

adamw

object UserModel {
  def findById(id: Id @@ User): ConnectionIO[Option[User]] = {
    findBy(fr"id = $id")
  }

  def findByEmail(email: String @@ LowerCased): ConnectionIO[Option[User]] = {
    findBy(fr"email_lowercase = $email")
  }

  private def findBy(by: Fragment): ConnectionIO[Option[User]] = {

adamw

import io.circe.Decoder
import com.softwaremill.bootzooka.infrastructure.Json._

case class Register_IN(login: String, email: String, password: String)

implicitly[Decoder[Register_IN]]

adamw

import com.softwaremill.tagging.@@
import io.circe.generic.AutoDerivation
import io.circe.java8.time.{JavaTimeDecoders, JavaTimeEncoders}
import io.circe.{Decoder, Encoder, Printer}

object Json extends AutoDerivation with JavaTimeDecoders with JavaTimeEncoders {
  val noNullsPrinter: Printer = Printer.noSpaces.copy(dropNullValues = true)

  implicit def taggedStringEncoder[U]: Encoder[String @@ U] = 
    Encoder.encodeString.asInstanceOf[Encoder[String @@ U]]