Don't ake derived formats implicit by defaultv0.3.0

5 files changed, 95 insertions, 15 deletions

diff --git a/README.md b/README.md
index 3c15698..f7c2070 100644
--- a/README.md
+++ b/README.md
@@ -26,14 +26,14 @@ build.sbt:
 libraryDependencies += "xyz.driver" %% "spray-json-derivation" % "<latest version>"
 ```
 
-Define some case classes and mix `DerivedFormats` into your JSON
+Define some case classes and mix `ImplicitDerivedFormats` into your JSON
 protocol stack. That's it.
 
 ```scala
 import spray.json._
-import xyz.driver.json.DerivedFormats
+import xyz.driver.json.ImplicitDerivedFormats
 
-object Main extends App with DefaultJsonProtocol with DerivedFormats {
+object Main extends App with DefaultJsonProtocol with ImplicitDerivedFormats {
   
   // Simple case classes
 
@@ -70,10 +70,27 @@ object Main extends App with DefaultJsonProtocol with DerivedFormats {
 }
 ```
 
+It is also possible to summon derived formats explicitly by mixing in `DerivedFormats`instead of `ImplicitDerivedFormats`:
+```scala
+import spray.json._
+import xyz.driver.json.DerivedFormats
+
+object Main extends App with DefaultJsonProtocol with DerivedFormats {
+
+  case class A(x: Int)
+  case class B(a: A, str: String)
+
+  implicit val bFormat: RootJsonFormat[B] = jsonFormat[B]
+
+  println(B(A(42), "hello world").toJson.prettyPrint)
+```
+This will have the additional benefit of outputting a stacktrace in case a format cannot be derived, hence making debugging
+much easier.
+
 ## Documentation
 Check out the main file
 [DerivedFormats.scala](src/main/scala/DerivedFormats.scala) and the
-[test suite](src/test/scala/ProductTypeFormats.scala) for a complete
+[test suite](src/test/scala/ProductTypeFormatTests.scala) for a complete
 overview of the project.
 
 ## Development
diff --git a/src/main/scala/DerivedFormats.scala b/src/main/scala/DerivedFormats.scala
index cbfbd61..4339e5c 100644
--- a/src/main/scala/DerivedFormats.scala
+++ b/src/main/scala/DerivedFormats.scala
@@ -5,7 +5,7 @@ import spray.json._
 
 import scala.language.experimental.macros
 
-/** Mixin that enables automatic derivation of JSON formats for any product
+/** Mixin that enables derivation of JSON formats for any product
   * (case classes) or coproduct (sealed traits) types. */
 trait DerivedFormats { self: BasicFormats =>
   type Typeclass[T] = JsonFormat[T]
@@ -75,14 +75,17 @@ trait DerivedFormats { self: BasicFormats =>
     }
   }
 
-  implicit def derivedFormat[T]: RootJsonFormat[T] =
-    macro DerivedFormatHelper.derivedFormat[T]
+  def jsonFormat[T]: RootJsonFormat[T] =
+    macro DerivedFormatMacros.derivedFormat[T]
 
 }
 
-object DerivedFormats extends DerivedFormats with BasicFormats
+trait ImplicitDerivedFormats extends DerivedFormats { self: BasicFormats =>
+  implicit def implicitJsonFormat[T]: RootJsonFormat[T] =
+    macro DerivedFormatMacros.derivedFormat[T]
+}
 
-object DerivedFormatHelper {
+object DerivedFormatMacros {
   import scala.reflect.macros.whitebox._
 
   /** Utility that converts a magnolia-generated JsonFormat to a RootJsonFormat. */
diff --git a/src/test/scala/CoproductTypeFormats.scala b/src/test/scala/CoproductTypeFormatTests.scala
index 6496e00..ec9b3f5 100644
--- a/src/test/scala/CoproductTypeFormats.scala
+++ b/src/test/scala/CoproductTypeFormatTests.scala
@@ -4,7 +4,7 @@ import spray.json._
 
 import org.scalatest._
 
-class CoproductTypeFormats
+class CoproductTypeFormatTests
     extends FlatSpec
     with FormatTests
     with DefaultJsonProtocol
@@ -16,6 +16,8 @@ class CoproductTypeFormats
   case class Plus(lhs: Expr, rhs: Expr) extends Expr
   case object One extends Expr
 
+  implicit val exprFormat: RootJsonFormat[Expr] = jsonFormat[Expr]
+
   "No-parameter case class child" should behave like checkRoundtrip[Expr](
     Zero(),
     """{"type":"Zero"}"""
@@ -40,6 +42,8 @@ class CoproductTypeFormats
   sealed abstract class Keyword(`type`: String)
   case class If(`type`: String) extends Keyword(`type`)
 
+  implicit val keywordFormat: RootJsonFormat[Keyword] = jsonFormat[Keyword]
+
   "GADT with type field alias" should behave like checkRoundtrip[Keyword](
     If("class"),
     """{"kind":"If","type":"class"}"""
@@ -49,6 +53,8 @@ class CoproductTypeFormats
   sealed abstract trait Crazy
   case class CrazyType() extends Crazy
 
+  implicit val crazyFormat: RootJsonFormat[Crazy] = jsonFormat[Crazy]
+
   "GADT with special characters in type field" should behave like checkRoundtrip[
     Crazy](
     CrazyType(),
@@ -59,12 +65,15 @@ class CoproductTypeFormats
   case object A extends Enum
   case object B extends Enum
 
+  implicit val enumFormat: RootJsonFormat[Enum] = jsonFormat[Enum]
+
   "Enum" should behave like checkRoundtrip[List[Enum]](
     A :: B :: Nil,
     """[{"type":"A"}, {"type":"B"}]"""
   )
 
-  "Serializing as sealed trait an deserializing as child" should "work" in {
+  "Serializing as sealed trait and deserializing as child" should "work" in {
+    implicit val plusFormat: RootJsonFormat[Plus] = jsonFormat[Plus]
     val expr: Expr = Plus(Value(42), Plus(Zero(), One))
     assert(expr.toJson.convertTo[Plus] == expr)
   }
diff --git a/src/test/scala/ImplicitDerivedFormatTests.scala b/src/test/scala/ImplicitDerivedFormatTests.scala
new file mode 100644
index 0000000..9723cb0
--- /dev/null
+++ b/src/test/scala/ImplicitDerivedFormatTests.scala
@@ -0,0 +1,26 @@
+package xyz.driver.json
+
+import spray.json._
+
+import org.scalatest._
+
+class ImplicitDerivedFormatTests
+    extends FlatSpec
+    with FormatTests
+    with ImplicitDerivedFormats
+    with DefaultJsonProtocol {
+
+  case class B(x: Int, b: String, mp: Map[String, Int])
+  case class C(b: B)
+
+  "Simple parameter product" should behave like checkRoundtrip(
+    B(42, "Hello World", Map("a" -> 1, "b" -> -1024)),
+    """{ "x": 42, "b": "Hello World", "mp": { "a": 1, "b": -1024 } }"""
+  )
+
+  "Nested parameter product with custom child format" should behave like checkRoundtrip(
+    C(B(42, "Hello World", Map("a" -> 1, "b" -> -1024))),
+    """{"b" :{ "x": 42, "b": "Hello World", "mp": { "a": 1, "b": -1024 } } }"""
+  )
+
+}
diff --git a/src/test/scala/ProductTypeFormats.scala b/src/test/scala/ProductTypeFormatTests.scala
index 02fb554..b7d8d27 100644
--- a/src/test/scala/ProductTypeFormats.scala
+++ b/src/test/scala/ProductTypeFormatTests.scala
@@ -4,7 +4,7 @@ import spray.json._
 
 import org.scalatest._
 
-class ProductTypeFormats
+class ProductTypeFormatTests
     extends FlatSpec
     with FormatTests
     with DerivedFormats
@@ -16,6 +16,13 @@ class ProductTypeFormats
   case object D
   case class E(d: D.type)
   case class F(x: Int)
+  case class G(f: F)
+
+  implicit val aFormat: RootJsonFormat[A] = jsonFormat[A]
+  implicit val bFormat: RootJsonFormat[B] = jsonFormat[B]
+  implicit val cFormat: RootJsonFormat[C] = jsonFormat[C]
+  implicit val dFormat: RootJsonFormat[D.type] = jsonFormat[D.type]
+  implicit val eFormat: RootJsonFormat[E] = jsonFormat[E]
 
   "No-parameter product" should behave like checkRoundtrip(A(), "{}")
 
@@ -41,14 +48,32 @@ class ProductTypeFormats
 
   // custom format for F, that inverts the value of parameter x
   implicit val fFormat: RootJsonFormat[F] = new RootJsonFormat[F] {
-    override def write(f: F): JsValue = JsObject("x" -> JsNumber(-f.x))
+    override def write(f: F): JsValue = JsObject("y" -> f.x.toJson)
     override def read(js: JsValue): F =
-      F(-js.asJsObject.fields("x").convertTo[Int])
+      F(js.asJsObject.fields("y").convertTo[Int])
   }
 
   "Overriding with a custom format" should behave like checkRoundtrip(
     F(2),
-    """{"x":-2}"""
+    """{"y":2}"""
+  )
+
+  implicit val gFormat: RootJsonFormat[G] = jsonFormat[G]
+
+  "Derving a format with a custom child format" should behave like checkRoundtrip(
+    G(F(2)),
+    """{"f": {"y":2}}"""
+  )
+
+  case class H(x: Boolean)
+  case class I(h: H)
+
+  // there is no format defined for H, Magnolia will generate one automatically
+  implicit val iFormat: RootJsonFormat[I] = jsonFormat[I]
+
+  "Deriving a format that has no implicit child formats available" should behave like checkRoundtrip(
+    I(H(true)),
+    """{"h": {"x":true}}"""
   )
 
 }