Packages

  • package root
    Definition Classes
    root
  • package skunk

    Skunk is a functional data access layer for Postgres.

    Skunk is a functional data access layer for Postgres.

    Design principles:

    • Skunk doesn't use JDBC. It speaks the Postgres wire protocol. It will not work with any other database back end.
    • Skunk is asynchronous all the way down, via cats-effect, fs2, and ultimately nio. The high-level network layers (Protocol and Session) are safe to use concurrently.
    • Serialization to and from schema types is not typeclass-based, so there are no implicit derivations. Codecs are explicit, like parser combinators.
    • I'm not sweating arity abstraction that much. Pass a ~ b ~ c for three args and Void if there are no args. This may change in the future but it's fine for now.
    • Skunk uses Resource for lifetime-managed objects, which means it takes some discipline to avoid leaks, especially when working concurrently. May or may not end up being problematic.
    • I'm trying to write good Scaladoc this time.

    A minimal example follows. We construct a Resource that yields a Session, then use it.

    package example

import cats.effect._
import skunk._
import skunk.implicits._
import skunk.codec.numeric._

object Minimal extends IOApp {

  val session: Resource[IO, Session[IO]] =
    Session.single(
      host     = "localhost",
      port     = 5432,
      user     = "postgres",
      database = "world",
    )

  def run(args: List[String]): IO[ExitCode] =
    session.use { s =>
      for {
        n <- s.unique(sql"select 42".query(int4))
        _ <- IO(println(s"The answer is $n."))
      } yield ExitCode.Success
    }

}

    Continue reading for an overview of the library. It's pretty small.

    Definition Classes
    root
  • package codec
    Definition Classes
    skunk
  • package data
    Definition Classes
    skunk
  • package exception
    Definition Classes
    skunk
  • package net

    Skunk network stack, starting with BitVectorSocket at the bottom and ending with Protocol at the top (Session delegates all its work to Protocol).

    Skunk network stack, starting with BitVectorSocket at the bottom and ending with Protocol at the top (Session delegates all its work to Protocol). Everything is non-blocking.

    Definition Classes
    skunk
  • package syntax
    Definition Classes
    skunk
  • package util
    Definition Classes
    skunk
  • Channel
  • Codec
  • Command
  • Cursor
  • Decoder
  • Encoder
  • Fragment
  • PreparedCommand
  • PreparedQuery
  • Query
  • Session
  • SqlState
  • Statement
  • Transaction
  • Void
  • implicits
  • ~

final case class Query[A, B](sql: String, origin: Origin, encoder: Encoder[A], decoder: Decoder[B]) extends Statement[A] with Product with Serializable

SQL, parameter encoder, and row decoder for a statement that returns rows. We assume that sql has the same number of placeholders of the form $1, $2, etc., as the number of slots encoded by encoder, that sql selects the same number of columns are the number of slots decoded by decoder, and that the parameter and column types specified by encoder and decoder are consistent with the schema. The check methods on Session provide a means to verify this assumption.

You can construct a Query directly, although it is more typical to use the sql interpolator.

sql"SELECT name, age FROM person WHERE age > $int2".query(varchar ~ int2) // Query[Short, String ~ Short]
sql

A SQL statement returning no rows.

origin

The Origin where the sql was defined, if any.

encoder

An encoder for all parameters $1, $2, etc., in sql.

decoder

A decoder for selected columns.

Source
Query.scala
See also

StringContextOps for information on the sql interpolator.

Session for information on executing a Query.

Linear Supertypes
Serializable, Serializable, Product, Equals, Statement[A], AnyRef, Any
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Inherited
  1. Query
  2. Serializable
  3. Serializable
  4. Product
  5. Equals
  6. Statement
  7. AnyRef
  8. Any
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Visibility
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Instance Constructors

  1. new Query(sql: String, origin: Origin, encoder: Encoder[A], decoder: Decoder[B])

    sql

    A SQL statement returning no rows.

    origin

    The Origin where the sql was defined, if any.

    encoder

    An encoder for all parameters $1, $2, etc., in sql.

    decoder

    A decoder for selected columns.

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  6. def contramap[C](f: (C) ⇒ A): Query[C, B]

    Query is a contravariant functor in A.

  7. val decoder: Decoder[B]
  8. def dimap[C, D](f: (C) ⇒ A)(g: (B) ⇒ D): Query[C, D]

    Query is a profunctor.

  9. val encoder: Encoder[A]
    Definition Classes
    Query → Statement
  10. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  11. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  12. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  13. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  14. def map[D](g: (B) ⇒ D): Query[A, D]

    Query is a covariant functor in B.

  15. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  16. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  17. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  18. val origin: Origin
    Definition Classes
    Query → Statement
  19. val sql: String
    Definition Classes
    Query → Statement
  20. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  21. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  22. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  23. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()

Inherited from Serializable

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from Statement[A]

Inherited from AnyRef

Inherited from Any

Transformations

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