added bodyEither directive

core/src/main/scala/com/spingo/op_rabbit/Directives.scala

@@ -7,6 +7,7 @@ import scala.language.implicitConversions
 import shapeless._
 import com.spingo.op_rabbit.Binding._
 import com.spingo.op_rabbit.Exchange.ExchangeType
+import EnhancedTry._
 
 import scala.util.{Failure, Success, Try}
 
@@ -179,6 +180,27 @@ trait Directives {
     }
   }
 
+  /**
+  Extract the message body as a Either. Uses a [[com.spingo.op_rabbit.RabbitUnmarshaller RabbitUnmarshaller]] to deserialize.
+  In case the body cannot be unmarshalled, the exception is present in the Left of the Either.
+  In this way the client code can have the unmarshalling error reason.
+    Example:
+
+    {{{
+    bodyOpt(as[JobDescription]) { jobDescriptionEither => ...
+    }
+    }}}
+   */
+  def bodyEither[T](um: RabbitUnmarshaller[T]): Directive1[Either[Throwable, T]] = new Directive1[Either[Throwable, T]] {
+    def happly(fn: ::[Either[Throwable, T], HNil] => Handler): Handler = { (promise, delivery) =>
+      val dataTry = Try {
+        um.unmarshall(delivery.body, Option(delivery.properties.getContentType), Option(delivery.properties.getContentEncoding))
+      }
+
+      fn(dataTry.toEither :: HNil)(promise, delivery)
+    }
+  }
+
   /**
     Extract any arbitrary value from the delivery / Java RabbitMQ objects. Accepts a function which receives a Delivery and returns some value.
     */

core/src/main/scala/com/spingo/op_rabbit/EnhancedTry.scala

@@ -0,0 +1,10 @@
+package com.spingo.op_rabbit
+
+import scala.util.{Success, Try}
+
+object EnhancedTry {
+  implicit class EnhancedTryImpl[T](t: Try[T]) {
+    def toEither: Either[Throwable, T] =
+      t.transform(success => Success(Right(success)), exception => Success(Left(exception))).get
+  }
+}

core/src/test/scala/com/spingo/op_rabbit/DirectivesSpec.scala

@@ -107,6 +107,29 @@ class DirectivesSpec extends FunSpec with Matchers with Inside {
         }
       } should be (acked)
     }
+
+    it("yields the value for both directives when one is bodyEither") {
+      val delivery = testDelivery(body = "hi".getBytes, properties = Seq(ReplyTo("place")))
+      resultFor(delivery) {
+        (bodyEither(as[String]) & property(ReplyTo)) { (bodyEither, replyTo) =>
+          replyTo should be ("place")
+          bodyEither.right.get should be ("hi")
+          ack
+        }
+      } should be (acked)
+    }
+  }
+
+  describe("bodyEither") {
+    it("yields the value as an option") {
+      val delivery = testDelivery(body = "hi".getBytes)
+      resultFor(delivery) {
+        (bodyEither(as[String])) { (bodyEither) =>
+          bodyEither.right.get should be ("hi")
+          ack
+        }
+      } should be (acked)
+    }
   }
 
   describe("|") {