Bulletin

A library for automatically performing shallow merges on case classes. Treat your data structures to the latest updates!

Copyright 2016 Dave Gurnell. Licensed Apache 2.

Getting Started

Grab the code by adding the following to your build.sbt:

libraryDependencies += "com.davegurnell" %% "bulletin" % "<<VERSION>>"

Create two case classes representing a data structure and an update:

case class Person(
  id: Long,
  name: String,
  email: Option[String])

case class Update(
  name: Option[String],
  email: Option[Option[String]])

Create instances of those classes:

val person = Person(123L, "Bruce Wayne", Some("[email protected]"))
val update = Update(Some("Batman"), Some(None))

And merge them!

import bulletin._

val updated = person merge update
// updated: Person = Person(123L, "Batman", None)

No update function is required.

Bulletin matches fields in Update to fields in Person by name and type.

If a field in the update has the same type as a field in the original, it always overwrites the original.

If a field in the update is an Option of a field in the original, it overwrites the original iff it is set to Some.

If you try to merge a data structure that doesn't conform to the correct patterns, you'll get a compile error:

person merge "This isn't an update!"
// compile error:
//   Cannot update a Person with a String.
//   Check the field types match up,
//   or manually create a Merge instance for these types.