Generic JSON encoder for case-classes

docs/src/main/tut/04_library_scala.md

@@ -153,9 +153,6 @@ import org.apache.spark.SparkContext
 case class Foo(a: Int, b: String)
 
 object ComplexRootArgFn extends MistFn {
-
-  implicit val fooExt: RootExtractor[Foo] = encoding.generic.extractor[Foo]
-
   // expected input is json:
   //  {
   //    "a": 42,
@@ -296,6 +293,7 @@ It supports:
 - Unit
 - primitives: Short, Int, Long, Float, String, Double, Boolean
 - collections: Array, Seq, Map
+- Case classes
 - experimental: DataFrame, DataSet - *Warning* - return them only if you sure that they are small, otherwise it will lead to `OutOfMemory`
   ```scala
   import mist.api.encoding.spark._
@@ -331,20 +329,6 @@ class Foo(val a: Int, val b: String)
 val fooEnc: JsEncoder[Foo] = JsEncoder(foo => JsMap("a" -> foo.a.js, "b" -> foo.b.js))
 ```
 
-Also it's possible to automatically derive an encoder for case classes:
-```tut:silent
-import mist.api._
-import mist.api.encoding
-import mist.api.encoding._
-import mist.api.encoding.defaults._
-
-case class Bar(a: Int, b: String)
-case class Foo(x: Int, foos: Seq[Bar])
-
-implicit val barEnc: JsEncoder[Bar] = encoding.generic.encoder[Bar]
-implicit val fooEnc: JsEncoder[Foo] = encoding.generic.encoder[Foo]
-```
-
 #### Validation
 
 For example for calculating pi using dartboard method n should be at least positive number.

mist-lib/src/main/scala/mist/api/encoding/JsEncoder.scala

@@ -1,6 +1,7 @@
 package mist.api.encoding
 
 import mist.api.data._
+import shadedshapeless.Lazy
 
 import scala.annotation.implicitNotFound
 
@@ -36,6 +37,8 @@ trait defaultEncoders {
     case None => JsNull
   }
   implicit def mapEnc[A](implicit enc: JsEncoder[A]): JsEncoder[Map[String, A]] = JsEncoder(m => JsMap(m.mapValues(enc.apply)))
+
+  implicit def productEnc[A <: Product](implicit enc: Lazy[ObjectEncoder[A]]): JsEncoder[A] = JsEncoder(enc.value.apply)
 }
 
 object defaultEncoders extends defaultEncoders

mist-lib/src/main/scala/mist/api/encoding/JsExtractor.scala

@@ -2,6 +2,7 @@ package mist.api.encoding
 
 import mist.api._
 import mist.api.data._
+import shadedshapeless.Lazy
 
 import scala.annotation.implicitNotFound
 import scala.reflect.ClassTag
@@ -134,6 +135,12 @@ trait defaultExtractors {
 
     case value => Failed.invalidType(s"Map[String, ${ext.`type`}]", value.toString)
   }
+
+  implicit def productExtWithDefaults[A <: Product](implicit
+      ext: Lazy[ObjectExtractor[A]],
+      patcher: Lazy[DefaultsPatcher[A]]
+  ): RootExtractor[A] =
+    RootExtractor[A](ext.value.`type`)(js => ext.value.apply(patcher.value.apply(js)))
 }