Add Instant @@ TTL (#181)

* Add Instant @@ TimeToLive

* Documentation

* Add AWS documentation link

* Bump version to 0.7.0

Co-authored-by: Jannik Arndt <jannik.arndt@moia.io>

Author: saeltz

build.sbt

@@ -109,5 +109,5 @@ lazy val sonatypeSettings = {
 }
 
 lazy val mimaSettings = Seq(
-  mimaPreviousArtifacts := Set("io.moia" %% "scynamo" % "0.6.0")
-)
+  mimaPreviousArtifacts := Set("io.moia" %% "scynamo" % "0.7.0")
+)

docs/README.md

@@ -45,6 +45,16 @@ val result2 = for {
 } yield (encoded, decoded)
 ```
 
+5. (Optional) You can use a tagged type to use `Instant` for DynamoDB's _TimeToLive_ which [is based on epoch seconds](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/time-to-live-ttl-before-you-start.html#time-to-live-ttl-before-you-start-formatting).
+```scala mdoc
+import scynamo._
+import shapeless.tag.@@
+import java.time.Instant
+
+case class ExpriringUser(id: String, firstName: String, lastName: String, expiresAt: Instant @@ TimeToLive)
+```
+Be aware that you lose millisecond precision.
+
 You can also look at the [minimal
 example](#minimal-example-using-the-aws-sdk) below that uses the AWS
 SDK (v2) with `scynamo`.

src/main/scala/scynamo/ScynamoDecoder.scala

@@ -3,15 +3,15 @@ package scynamo
 import java.time.Instant
 import java.util.UUID
 import java.util.concurrent.TimeUnit
-
 import cats.data.{EitherNec, NonEmptyChain}
 import cats.syntax.either._
 import cats.syntax.parallel._
 import cats.{Monad, SemigroupK}
 import scynamo.StackFrame.Index
 import scynamo.generic.auto.AutoDerivationUnlocked
 import scynamo.generic.{GenericScynamoDecoder, SemiautoDerivationDecoder}
-import shapeless.Lazy
+import shapeless.{tag, Lazy}
+import shapeless.tag.@@
 import software.amazon.awssdk.services.dynamodb.model.AttributeValue
 
 import scala.annotation.tailrec
@@ -124,6 +124,13 @@ trait DefaultScynamoDecoderInstances extends ScynamoDecoderFunctions with Scynam
         result  <- convert(nstring, "Long")(_.toLong)
       } yield Instant.ofEpochMilli(result)
 
+  implicit val instantTtlDecoder: ScynamoDecoder[Instant @@ TimeToLive] =
+    attributeValue =>
+      for {
+        nstring <- attributeValue.asEither(ScynamoType.Number)
+        result  <- convert(nstring, "Long")(_.toLong)
+      } yield tag[TimeToLive][Instant](Instant.ofEpochSecond(result))
+
   implicit def seqDecoder[A: ScynamoDecoder]: ScynamoDecoder[scala.collection.immutable.Seq[A]] = iterableDecoder
 
   implicit def listDecoder[A: ScynamoDecoder]: ScynamoDecoder[List[A]] = iterableDecoder

src/main/scala/scynamo/ScynamoEncoder.scala

@@ -1,17 +1,17 @@
 package scynamo
 
-import java.time.Instant
-import java.util.UUID
-
 import cats.data.EitherNec
 import cats.syntax.either._
 import cats.syntax.parallel._
 import scynamo.StackFrame.{Index, MapKey}
 import scynamo.generic.auto.AutoDerivationUnlocked
 import scynamo.generic.{GenericScynamoEncoder, SemiautoDerivationEncoder}
 import shapeless._
+import shapeless.tag.@@
 import software.amazon.awssdk.services.dynamodb.model.AttributeValue
 
+import java.time.Instant
+import java.util.UUID
 import scala.concurrent.duration.{Duration, FiniteDuration}
 import scala.jdk.CollectionConverters._
 
@@ -46,6 +46,9 @@ trait DefaultScynamoEncoderInstances extends ScynamoIterableEncoder {
 
   implicit val instantEncoder: ScynamoEncoder[Instant] = numberStringEncoder.contramap[Instant](_.toEpochMilli.toString)
 
+  implicit val instantTtlEncoder: ScynamoEncoder[Instant @@ TimeToLive] =
+    numberStringEncoder.contramap[Instant @@ TimeToLive](_.getEpochSecond.toString)
+
   implicit val uuidEncoder: ScynamoEncoder[UUID] = stringEncoder.contramap[UUID](_.toString)
 
   implicit def seqEncoder[A: ScynamoEncoder]: ScynamoEncoder[scala.collection.immutable.Seq[A]] =

src/main/scala/scynamo/TimeToLive.scala

@@ -0,0 +1,3 @@
+package scynamo
+
+sealed trait TimeToLive

src/test/scala/scynamo/ScynamoCodecProps.scala

@@ -1,14 +1,15 @@
 package scynamo
 
-import java.time.Instant
-import java.util.UUID
-
 import org.scalacheck.Prop.propBoolean
 import org.scalacheck.{Gen, Prop, Properties}
 import scynamo.ScynamoCodecProps.Shape
 import scynamo.generic.semiauto._
 import scynamo.wrapper.{ScynamoNumberSet, ScynamoStringSet}
+import shapeless.tag
 
+import java.time.Instant
+import java.time.temporal.ChronoUnit
+import java.util.UUID
 import scala.concurrent.duration.Duration
 
 class ScynamoCodecProps extends Properties("ScynamoCodec") {
@@ -46,6 +47,11 @@ class ScynamoCodecProps extends Properties("ScynamoCodec") {
     decodeAfterEncodeIsIdentity(value)
   }
 
+  propertyWithSeed("decode.encode === id (instant @@ ttl)", propertySeed) =
+    Prop.forAll(Gen.calendar.map(_.toInstant.truncatedTo(ChronoUnit.SECONDS)).map(tag[TimeToLive][Instant](_))) { value =>
+      decodeAfterEncodeIsIdentity(value)
+    }
+
   propertyWithSeed("decode.encode === id (seq)", propertySeed) = Prop.forAll { value: scala.collection.immutable.Seq[Int] =>
     decodeAfterEncodeIsIdentity(value)
   }