Merge pull request #31 from MasseGuillaume/feature/obj-getOption

Add Conf.Obj.getOption[T](field: String)

metaconfig-core/shared/src/main/scala/metaconfig/Conf.scala

@@ -45,6 +45,14 @@ object Conf {
       Obj(values.map {
         case (k, v) => k -> f(v)
       })
+    def getOption[T](path: String, extraNames: String*)(
+        implicit ev: ConfDecoder[T]): Configured[Option[T]] =
+      Metaconfig
+        .getKey(this, path +: extraNames)
+        .map(
+          value => ev.read(value).map(Some(_))
+        )
+        .getOrElse(Configured.Ok(None))
   }
   object Obj {
     val empty = Obj()

metaconfig-core/shared/src/test/scala/metaconfig/ConfOptionTest.scala

@@ -0,0 +1,30 @@
+package metaconfig
+
+import org.scalatest.FunSuite
+
+case class Foo(a: Option[String])
+object Foo {
+  implicit val reader: ConfDecoder[Foo] =
+    ConfDecoder.instance[Foo] {
+      case obj: Conf.Obj =>
+        obj.getOption[String]("a").map(Foo(_))
+    }
+}
+
+class ConfOptionTest extends FunSuite {
+  import Conf._
+
+  test("simple") {
+    val conf = Obj("a" -> Str("b"))
+    val obtained = conf.as[Foo].get
+    val expected = Foo(Some("b"))
+    assert(obtained == expected)
+  }
+
+  test("missing") {
+    val conf = Obj()
+    val obtained = conf.as[Foo].get
+    val expected = Foo(None)
+    assert(obtained == expected)
+  }
+}