CODEWITHSUNDEEP
scalaplayframework
MasseElch
MasseElch

Reputation: 21

Play-Slick Repository Pattern

I am trying to implement a simple Repository in a PlayFramework app with the play-slick plugin.

I am new to scala, new to slick, new to play.

When trying to compile my code, i get the following error:

type mismatch;
 found   : slick.lifted.TableQuery[UserRepository.this.UserTable]
 required: UserRepository.this.profile.api.TableQuery[UserRepository.this.BaseTable]
    (which expands to)  slick.lifted.TableQuery[UserRepository.this.BaseTable]
Note: UserRepository.this.UserTable <: UserRepository.this.BaseTable, but class TableQuery is invariant in type E.
You may wish to define E as +E instead. (SLS 4.5)

Here is my code:

trait BaseEntity {
  def id: Long
  def createdAt: LocalDateTime
  def updatedAt: LocalDateTime
  def deletedAt: LocalDateTime
}
case class User (id: Long, firstname: String, lastname: String, password: String, createdAt: LocalDateTime, updatedAt: LocalDateTime, deletedAt: LocalDateTime) extends BaseEntity

abstract class BaseRepository[E <: BaseEntity](protected val dbConfigProvider: DatabaseConfigProvider, executionContext: ExecutionContext) extends HasDatabaseConfigProvider[JdbcProfile] {

  import profile.api._

  implicit val localDateTimeToTimestamp: BaseColumnType[LocalDateTime] = MappedColumnType.base[LocalDateTime, Timestamp](
    l => Timestamp.valueOf(l),
    t => t.toLocalDateTime
  )

  protected abstract class BaseTable(tag: Tag, tableName: String) extends Table[E](tag, tableName) {
    def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
    def createdAt = column[LocalDateTime]("created_at")
    def updatedAt = column[LocalDateTime]("updated_at")
    def deletedAt = column[LocalDateTime]("deleted_at")
  }

  protected val query: TableQuery[BaseTable]

  def all(): Future[Seq[E]] = db.run(query.result)
}

class UserRepository @Inject()(@NamedDatabase("effective-potato-play") override protected val dbConfigProvider: DatabaseConfigProvider)(implicit executionContext: ExecutionContext) extends BaseRepository[User](dbConfigProvider, executionContext) {

  import profile.api._

  protected class UserTable(tag: Tag) extends BaseTable(tag, "user") {
    def firstname = column[String]("firstname")
    def lastname = column[String]("lastname")
    def password = column[String]("password")
    def * = (id, firstname, lastname, password, createdAt, updatedAt, deletedAt) <> (User.tupled, User.unapply)
  }

  protected val query = TableQuery[UserTable]
}

Upvotes: 1

Views: 917

Answers (1)

MasseElch
MasseElch

Reputation: 21

pamus comment led me in the right directions.

I solved the following by moving the inner Table-Class to an own class and giving the query for the repository as constructor argument. 

abstract class BaseRepository[E <: BaseEntity, T <: BaseTable[E]](val dbConfigProvider: DatabaseConfigProvider, executionContext: ExecutionContext, query: TableQuery[T]) extends HasDatabaseConfigProvider[JdbcProfile] {
  def all(): Future[Seq[E]] = db.run(query.result)
  def find(id: Long): Future[Option[E]] = db.run(query.filter(_.id === id).result.headOption)
}

class UserRepository @Inject()(dbConfigProvider: DatabaseConfigProvider)(implicit executionContext: ExecutionContext) extends BaseRepository[User, UserTable](dbConfigProvider, executionContext, TableQuery[UserTable]) {

}

abstract class BaseTable[E <: BaseEntity](tag: Tag, tableName: String) extends Table[E](tag, tableName) {
  implicit val localDateTimeToTimestamp: BaseColumnType[LocalDateTime] = MappedColumnType.base[LocalDateTime, Timestamp](
    l => Timestamp.valueOf(l),
    t => t.toLocalDateTime
  )
  def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
  def createdAt = column[LocalDateTime]("created_at")
  def updatedAt = column[LocalDateTime]("updated_at")
  def deletedAt = column[Option[LocalDateTime]]("deleted_at", O.Default(null))
}
class UserTable(tag: Tag) extends BaseTable[User](tag, "user") {
  def firstname = column[String]("firstname")
  def lastname = column[String]("lastname")
  def password = column[String]("password")
  def * = (id, firstname, lastname, password, createdAt, updatedAt, deletedAt) <> (User.tupled, User.unapply)
}

I can then use the queries from the BaseRepository like so

userRepository.find(1).map { user =>
  Ok(Json.toJson(user))
}

Upvotes: 1

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