v0.4.2

• Query complexity calculation mechanism is implemented (#85). This mechanism makes a rough estimation of the query complexity before it is executed.
  Every field in the query gets a default score 1.0. The "complexity" of the query is the sum of all field scores. You can customize the
  field score with complexity argument:

  Field("pets", OptionType(ListType(PetType)),
    arguments = Argument("limit", IntType) :: Nil,
    complexity = Some((args, childrenScore) ⇒ 25.0D + args.arg[Int]("limit") * childrenScore),
    resolve = ctx ⇒ ...)

  If you would like to use this feature, you need to provide measureComplexity argument to the Executor. For example:

  val rejectComplexQueries = (c: Double) ⇒
    if (c > 1000)
      throw new IllegalArgumentException(s"Too complex query: max allowed complexity is 1000.0, but got $c")
    else ()
  
  val exceptionHandler: PartialFunction[(ResultMarshaller, Throwable), HandledException] = {
    case (m, e: IllegalArgumentException) ⇒ HandledException(e.getMessage)
  }
  
  Executor.execute(schema, query,
    exceptionHandler = exceptionHandler,
    measureComplexity = Some(rejectComplexQueries))

  The complexity of full introspection query (used by tools like GraphiQL) is 102.0.
  You can find more information in the docs: Protection Against Malicious Queries

• json4s-jackson is now supported in addition to native (#84). This results in minor import change:

  // before
  
  sangria.integration.json4s._
  
  // after
  
  // either (same behaviour as before)
  sangria.integration.json4s.native._
  
  //or
  sangria.integration.json4s.jackson._

• json4s is updated to version 3.3.0 (#84)

• Provide a helpful error messages if schema has a broken circular references (which cause fields to be null) (#83)