Derivation of DynamoFormat is not automatic anymore

Auto derivation of case classes now requires `import com.gu.scanamo.auto._`
and doesn't come automatically as soon as DynamoFormat is in scope
The goal is to keep providing the automatic derivation of DynamoFormat
for case classes without forcing it on scanamo users

README.md

@@ -25,6 +25,7 @@ Note: the `LocalDynamoDB` object is provided by the `scanamo-testkit` package.
 ```scala
 scala> import com.gu.scanamo._
 scala> import com.gu.scanamo.syntax._
+scala> import com.gu.scanamo.auto._
 
 scala> val client = LocalDynamoDB.client()
 scala> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._

alpakka/src/test/scala/com/gu/scanamo/ScanamoAlpakkaSpec.scala

@@ -9,6 +9,7 @@ import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
 import com.gu.scanamo.ops.ScanamoOps
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 import org.scalatest.concurrent.ScalaFutures
 import org.scalatest.time.{Millis, Seconds, Span}
 import org.scalatest.{BeforeAndAfterAll, FunSpecLike, Matchers}

cats/src/test/scala/com/gu/scanamo/ScanamoCatsSpec.scala

@@ -11,6 +11,7 @@ import com.gu.scanamo.error.DynamoReadError
 import com.gu.scanamo.ops.ScanamoOps
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 
 class ScanamoCatsSpec extends FunSpec with Matchers {
 

docs/src/main/tut/dynamo-format.md

@@ -16,6 +16,25 @@ Scanamo also supports automatically deriving formats for case classes and
 sealed trait families where all the contained types have a defined or derivable
 `DynamoFormat`.
 
+### Automatic Derivation
+
+Scanamo can automatically derive `DynamoFormat` for case classes (as long as all its members can also be derived). Ex:
+
+```tut:silent
+import com.gu.scanamo.auto._
+
+case class Farm(animals: List[String])
+case class Farmer(name: String, age: Long, farm: Farm)
+
+val table = Table[Farmer]("farmer")
+table.putAll(
+    Set(
+        Farmer("McDonald", 156L, Farm(List("sheep", "cow"))),
+        Farmer("Boggis", 43L, Farm(List("chicken")))
+    )
+)
+```
+
 ### Custom Formats
 
 It's also possible to define a serialisation format for types which Scanamo

formats/src/main/scala/com/gu/scanamo/DerivedDynamoFormat.scala

@@ -4,6 +4,7 @@ import cats.data.{NonEmptyList, Validated}
 import cats.syntax.either._
 import com.amazonaws.services.dynamodbv2.model.AttributeValue
 import com.gu.scanamo.error._
+import com.gu.scanamo.export.Exported
 import shapeless._
 import shapeless.labelled._
 
@@ -95,18 +96,22 @@ trait DerivedDynamoFormat {
   implicit def genericProduct[T: NotSymbol, R](
     implicit gen: LabelledGeneric.Aux[T, R],
     formatR: Lazy[ValidConstructedDynamoFormat[R]]
-  ): DynamoFormat[T] =
-    new DynamoFormat[T] {
-      def read(av: AttributeValue): Either[DynamoReadError, T] = formatR.value.read(av).map(gen.from).toEither
-      def write(t: T): AttributeValue = formatR.value.write(gen.to(t))
-    }
+  ): Exported[DynamoFormat[T]] =
+    Exported(
+      new DynamoFormat[T] {
+        def read(av: AttributeValue): Either[DynamoReadError, T] = formatR.value.read(av).map(gen.from).toEither
+        def write(t: T): AttributeValue = formatR.value.write(gen.to(t))
+      }
+    )
 
   implicit def genericCoProduct[T, R](
     implicit gen: LabelledGeneric.Aux[T, R],
     formatR: Lazy[CoProductDynamoFormat[R]]
-  ): DynamoFormat[T] =
-    new DynamoFormat[T] {
-      def read(av: AttributeValue): Either[DynamoReadError, T] = formatR.value.read(av).map(gen.from)
-      def write(t: T): AttributeValue = formatR.value.write(gen.to(t))
-    }
+  ): Exported[DynamoFormat[T]] =
+    Exported(
+      new DynamoFormat[T] {
+        def read(av: AttributeValue): Either[DynamoReadError, T] = formatR.value.read(av).map(gen.from)
+        def write(t: T): AttributeValue = formatR.value.write(gen.to(t))
+      }
+    )
 }

formats/src/main/scala/com/gu/scanamo/DynamoFormat.scala

@@ -29,9 +29,9 @@ import scala.reflect.ClassTag
   * Right(List(Some(1), None, Some(3)))
   * }}}
   *
-  * Also supports automatic derivation for case classes
-  *
   * {{{
+  * >>> import com.gu.scanamo.auto._
+  * >>>
   * >>> case class Farm(animals: List[String])
   * >>> case class Farmer(name: String, age: Long, farm: Farm)
   * >>> val farmerF = DynamoFormat[Farmer]

formats/src/main/scala/com/gu/scanamo/EnumerationDynamoFormat.scala

@@ -2,7 +2,8 @@ package com.gu.scanamo
 
 import com.amazonaws.services.dynamodbv2.model.AttributeValue
 import com.gu.scanamo.error.{DynamoReadError, TypeCoercionError}
-import shapeless.labelled.{field, FieldType}
+import com.gu.scanamo.export.Exported
+import shapeless.labelled.{FieldType, field}
 import shapeless.{:+:, CNil, Coproduct, HNil, Inl, Inr, LabelledGeneric, Witness}
 
 abstract class EnumerationDynamoFormat[T] extends DynamoFormat[T]
@@ -26,7 +27,7 @@ abstract class EnumerationDynamoFormat[T] extends DynamoFormat[T]
   * Zebra
   * }}}
   */
-trait EnumDynamoFormat extends DerivedDynamoFormat {
+trait EnumDynamoFormat extends LowPriorityDynamoFormat {
   implicit val enumDynamoFormatCNil: EnumerationDynamoFormat[CNil] = new EnumerationDynamoFormat[CNil] {
     override def read(av: AttributeValue): Either[DynamoReadError, CNil] = Left(
       TypeCoercionError(new Exception(s"$av is not a recognised member of the Enumeration"))
@@ -61,3 +62,8 @@ trait EnumDynamoFormat extends DerivedDynamoFormat {
       override def write(t: A): AttributeValue = genericFormat.write(gen.to(t))
     }
 }
+
+trait LowPriorityDynamoFormat {
+  implicit def dynamoFormat[T](implicit exported: Exported[DynamoFormat[T]]): DynamoFormat[T] =
+    exported.instance
+}

formats/src/main/scala/com/gu/scanamo/auto.scala

@@ -0,0 +1,9 @@
+package com.gu.scanamo
+
+/**
+  * Fully automatic format derivation.
+  *
+  * Importing the contents of this package object provides [[com.gu.scanamo.DynamoFormat]]
+  * instances for case classes (if all members have instances)
+  */
+package object auto extends DerivedDynamoFormat

formats/src/main/scala/com/gu/scanamo/export/Exported.scala

@@ -0,0 +1,3 @@
+package com.gu.scanamo.export
+
+final case class Exported[T](instance: T) extends AnyVal

formats/src/test/scala/com/gu/scanamo/DynamoFormatTest.scala

@@ -8,6 +8,7 @@ import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
 import org.scalacheck._
 import org.scalatest._
 import org.scalatest.prop.GeneratorDrivenPropertyChecks
+import com.gu.scanamo.auto._
 
 class DynamoFormatTest extends FunSpec with Matchers with GeneratorDrivenPropertyChecks {
 

scalaz-zio/src/test/scala/com/gu/scanamo/ScanamoZioSpec.scala

@@ -9,6 +9,7 @@ import com.gu.scanamo.error.DynamoReadError
 import com.gu.scanamo.ops.ScanamoOps
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 import cats.implicits._
 import scalaz.zio.{IO, RTS}
 

scalaz/src/test/scala/com/gu/scanamo/ScanamoScalazSpec.scala

@@ -7,6 +7,7 @@ import com.gu.scanamo.error.DynamoReadError
 import com.gu.scanamo.ops.ScanamoOps
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 import scalaz.ioeffect.RTS
 import scalaz._
 import Scalaz._

scanamo/src/main/scala/com/gu/scanamo/Scanamo.scala

@@ -15,6 +15,8 @@ object Scanamo {
     * provided synchronously
     *
     * {{{
+    * >>> import com.gu.scanamo.auto._
+    *
     * >>> case class Transport(mode: String, line: String)
     * >>> val transport = Table[Transport]("transport")
     *

scanamo/src/main/scala/com/gu/scanamo/SecondaryIndex.scala

@@ -27,6 +27,7 @@ sealed abstract class SecondaryIndex[V] {
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)('name -> S)('antagonist -> S) { (t, i) =>
     * ...   val table = Table[Bear](t)
@@ -53,6 +54,7 @@ sealed abstract class SecondaryIndex[V] {
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)('organisation -> S, 'repository -> S)('language -> S, 'license -> S) { (t, i) =>
     * ...   val githubProjects = Table[GithubProject](t)
@@ -81,6 +83,7 @@ sealed abstract class SecondaryIndex[V] {
     * >>> val client = LocalDynamoDB.client()
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)(
     * ...   'mode -> S, 'line -> S)('mode -> S, 'colour -> S
@@ -114,6 +117,7 @@ sealed abstract class SecondaryIndex[V] {
     * >>> val client = LocalDynamoDB.client()
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)(
     * ...   'mode -> S, 'line -> S)('mode -> S, 'colour -> S

scanamo/src/main/scala/com/gu/scanamo/Table.scala

@@ -20,6 +20,7 @@ import scala.collection.JavaConverters._
   *
   * >>> LocalDynamoDB.withRandomTable(client)('mode -> S, 'line -> S) { t =>
   * ...   import com.gu.scanamo.syntax._
+  * ...   import com.gu.scanamo.auto._
   * ...   val transport = Table[Transport](t)
   * ...   val operations = for {
   * ...     _ <- transport.putAll(Set(
@@ -50,6 +51,8 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
+    *
     * >>> val client = LocalDynamoDB.client()
     *
     * >>> val dataSet = Set(
@@ -79,6 +82,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> val client = LocalDynamoDB.client()
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)('mode -> S, 'line -> S)('colour -> S) { (t, i) =>
     * ...   val transport = Table[Transport](t)
@@ -97,6 +101,8 @@ case class Table[V: DynamoFormat](name: String) {
     * {{{
     * >>> case class GithubProject(organisation: String, repository: String, language: String, license: String)
     *
+    * >>> import com.gu.scanamo.auto._
+    *
     * >>> LocalDynamoDB.withRandomTableWithSecondaryIndex(client)('organisation -> S, 'repository -> S)('language -> S, 'license -> S) { (t, i) =>
     * ...   val githubProjects = Table[GithubProject](t)
     * ...   val operations = for {
@@ -129,6 +135,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('location -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val forecast = Table[Forecast](t)
     * ...   val operations = for {
     * ...     _ <- forecast.put(Forecast("London", "Rain"))
@@ -146,6 +153,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val characters = Table[Character](t)
     * ...   val operations = for {
     * ...     _ <- characters.put(Character("The Doctor", List("Ecclestone", "Tennant", "Smith")))
@@ -163,6 +171,7 @@ case class Table[V: DynamoFormat](name: String) {
     * {{{
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val characters = Table[Character](t)
     * ...   val operations = for {
     * ...     _ <- characters.update('name -> "James Bond", append('actors -> "Craig"))
@@ -180,6 +189,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('kind -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val fruits = Table[Fruit](t)
     * ...   val operations = for {
     * ...     _ <- fruits.put(Fruit("watermelon", List("USA")))
@@ -198,6 +208,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val foos = Table[Foo](t)
     * ...   val operations = for {
     * ...     _ <- foos.put(Foo("x", 0, List("First")))
@@ -215,6 +226,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val bars = Table[Bar](t)
     * ...   val operations = for {
     * ...     _ <- bars.put(Bar("x", 1L, Set("First")))
@@ -235,6 +247,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('id -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val outers = Table[Outer](t)
     * ...   val id = java.util.UUID.fromString("a8345373-9a93-43be-9bcd-e3682c9197f4")
     * ...   val operations = for {
@@ -254,6 +267,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('id -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val things = Table[Thing](t)
     * ...   val operations = for {
     * ...     _ <- things.put(Thing("a1", 3, None))
@@ -277,6 +291,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * >>> LocalDynamoDB.withRandomTable(client)('mode -> S, 'line -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val transport = Table[Transport](t)
     * ...   val operations = for {
     * ...     _ <- transport.putAll(Set(
@@ -305,6 +320,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> val client = LocalDynamoDB.client()
     * >>> val (get, scan, query) = LocalDynamoDB.withRandomTable(client)('country -> S, 'name -> S) { t =>
     * ...   import com.gu.scanamo.syntax._
+    * ...   import com.gu.scanamo.auto._
     * ...   val cityTable = Table[City](t)
     * ...   val ops = for {
     * ...     putRes <- cityTable.putAll(Set(
@@ -335,6 +351,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> case class Farmer(name: String, age: Long, farm: Farm)
     *
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     * >>> import com.gu.scanamo.query._
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> val client = LocalDynamoDB.client()
@@ -491,6 +508,7 @@ case class Table[V: DynamoFormat](name: String) {
     *
     * {{{
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     * >>> import com.gu.scanamo.query._
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     * >>> val client = LocalDynamoDB.client()
@@ -547,6 +565,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
+    * ...   import com.gu.scanamo.auto._
     * ...   val table = Table[Bear](t)
     * ...   val ops = for {
     * ...     _ <- table.put(Bear("Pooh", "honey"))
@@ -577,6 +596,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> import com.gu.scanamo.error._
     * >>> import com.gu.scanamo.ops._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     * >>> import com.gu.scanamo.query._
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
@@ -609,6 +629,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> val client = LocalDynamoDB.client()
     *
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
     * >>> LocalDynamoDB.withRandomTable(client)('mode -> S, 'line -> S) { t =>
@@ -645,6 +666,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> import com.gu.scanamo.error._
     * >>> import com.gu.scanamo.ops._
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     * >>> import com.gu.scanamo.query._
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
@@ -681,6 +703,7 @@ case class Table[V: DynamoFormat](name: String) {
     * >>> import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
     *
     * >>> import com.gu.scanamo.syntax._
+    * >>> import com.gu.scanamo.auto._
     *
     * >>> LocalDynamoDB.withRandomTable(client)('name -> S) { t =>
     * ...   val table = Table[Bear](t)

scanamo/src/test/scala/com/gu/scanamo/ScanamoAsyncTest.scala

@@ -8,6 +8,7 @@ import org.scalatest.{BeforeAndAfterAll, FunSpec, Matchers}
 import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType._
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 
 class ScanamoAsyncTest extends FunSpec with Matchers with BeforeAndAfterAll with ScalaFutures {
   implicit val defaultPatience =

scanamo/src/test/scala/com/gu/scanamo/ScanamoTest.scala

@@ -11,6 +11,7 @@ import com.gu.scanamo.error.DynamoReadError
 import com.gu.scanamo.ops.ScanamoOps
 import com.gu.scanamo.query._
 import com.gu.scanamo.syntax._
+import com.gu.scanamo.auto._
 
 class ScanamoTest extends org.scalatest.FunSpec with org.scalatest.Matchers {