DynamoFormat

Type class for defining serialisation to and from DynamoDB's AttributeValue

>>> val listOptionFormat = DynamoFormat[List[Option[Int]]]
>>> listOptionFormat.read(listOptionFormat.write(List(Some(1), None, Some(3))))
Right(List(Some(1), None, Some(3)))

Also supports automatic derivation for case classes

>>> case class Farm(animals: List[String])
>>> case class Farmer(name: String, age: Long, farm: Farm)
>>> val farmerF = DynamoFormat[Farmer]
>>> farmerF.read(farmerF.write(Farmer("McDonald", 156L, Farm(List("sheep", "cow")))))
Right(Farmer(McDonald,156,Farm(List(sheep, cow))))

and for sealed trait + case object hierarchies

>>> sealed trait Animal
>>> case object Aardvark extends Animal
>>> case object Zebra extends Animal
>>> case class Pet(name: String, animal: Animal)
>>> val petF = DynamoFormat[Pet]
>>> petF.read(petF.write(Pet("Amy", Aardvark)))
Right(Pet(Amy,Aardvark))

>>> petF.read(petF.write(Pet("Zebediah", Zebra)))
Right(Pet(Zebediah,Zebra))

Problems reading a value are detailed

>>> import cats.syntax.either._

>>> case class Developer(name: String, age: String, problems: Int)
>>> val invalid = DynamoFormat[Farmer].read(DynamoFormat[Developer].write(Developer("Alice", "none of your business", 99)))
>>> invalid
Left(InvalidPropertiesError(NonEmptyList(PropertyReadError(age,NoPropertyOfType(N,{S: none of your business,})), PropertyReadError(farm,MissingProperty))))

>>> invalid.leftMap(cats.Show[error.DynamoReadError].show)
Left('age': not of type: 'N' was '{S: none of your business,}', 'farm': missing)

Optional properties are defaulted to None

>>> case class LargelyOptional(a: Option[String], b: Option[String])
>>> DynamoFormat[LargelyOptional].read(DynamoFormat[Map[String, String]].write(Map("b" -> "X")))
Right(LargelyOptional(None,Some(X)))

Custom formats can often be most easily defined using DynamoFormat.coercedXmap, DynamoFormat.xmap or DynamoFormat.iso