add new lens `arrayOrSingletonAsArray` which reinterprets non json array values as singleton arrays, fixes #8

5 files changed, 74 insertions, 1 deletions

diff --git a/README.md b/README.md
index 26f0cf5..b053a7f 100644
--- a/README.md
+++ b/README.md
@@ -184,6 +184,8 @@ from the following list.
    and its field `fullName` is a string starting with `"Joe"`.
  * `allMatching(next: Lens)`: A combination of `combine` and `elements`. Selects elements matching the `next` lens
    and then applies the `next` lens.
+ * `arrayOrSingletonAsArray`: Makes sure that the result is always a json array by interpreting a value that is no array
+   as an singleton array containing just that value.
 
 ##### Combination
 
diff --git a/notes/0.5.4.markdown b/notes/0.5.4.markdown
new file mode 100644
index 0000000..861208a
--- /dev/null
+++ b/notes/0.5.4.markdown
@@ -0,0 +1,7 @@
+New features in this version:
+
+  - [#8][] added `arrayOrSingletonAsArray` which allows to reinterpret values as singleton arrays
+  - [#11][] fixed a parser bug in JsonPathParser
+
+[#8]: https://github.com/jrudolph/json-lenses/issues/8
+[#11]: https://github.com/jrudolph/json-lenses/issues/11
diff --git a/src/main/scala/spray/json/lenses/ScalarLenses.scala b/src/main/scala/spray/json/lenses/ScalarLenses.scala
index 3a85147..4beee27 100644
--- a/src/main/scala/spray/json/lenses/ScalarLenses.scala
+++ b/src/main/scala/spray/json/lenses/ScalarLenses.scala
@@ -55,6 +55,20 @@ trait ScalarLenses {
 
     def retr: JsValue => SafeJsValue = x => Right(x)
   }
+
+  /**
+   * A lens which leaves JsArray as is but transforms any other kind of JsValue into
+   * a singleton JsArray with that value as single element.
+   */
+  val arrayOrSingletonAsArray: ScalarLens = new LensImpl[Id] {
+    def updated(f: SafeJsValue => SafeJsValue)(parent: JsValue): SafeJsValue =
+      retr(parent).flatMap(x => f(Right(x)))
+
+    def retr: JsValue => Validated[JsValue] = {
+      case ar: JsArray => Right(ar)
+      case x => Right(JsArray(x))
+    }
+  }
 }
 
-object ScalarLenses extends ScalarLenses
\ No newline at end of file
+object ScalarLenses extends ScalarLenses
diff --git a/src/test/scala/spray/json/lenses/JsonLensesSpec.scala b/src/test/scala/spray/json/lenses/JsonLensesSpec.scala
index 780083c..9418fb1 100644
--- a/src/test/scala/spray/json/lenses/JsonLensesSpec.scala
+++ b/src/test/scala/spray/json/lenses/JsonLensesSpec.scala
@@ -66,6 +66,20 @@ class JsonLensesSpec extends Specification with SpecHelpers {
           }
         }
       }
+      "orSingletonArray" in {
+        "empty JsArray" in {
+          "[]".extract[Seq[Int]](arrayOrSingletonAsArray) === Nil
+        }
+        "filled JsArray" in {
+          "[1,2,3,4,5]".extract[Seq[Int]](arrayOrSingletonAsArray) === Seq(1, 2, 3, 4, 5)
+        }
+        "single int value" in {
+          "5".extract[Seq[Int]](arrayOrSingletonAsArray) === Seq(5)
+        }
+        "single object value" in {
+          """{ "a": 5 }""".extract[Seq[Map[String, Int]]](arrayOrSingletonAsArray) === Seq(Map("a" -> 5))
+        }
+      }
       "all elements of an array" in {
         "simple" in {
           """[18, 23, 2, 5, 8, 3]""".extract[Int](*) must be_==(Seq(18, 23, 2, 5, 8, 3))
@@ -88,6 +102,7 @@ class JsonLensesSpec extends Specification with SpecHelpers {
           """{"a": 5}""".extract[Int](("a" / *)) must throwAn[Exception]( """Not a json array: 5""")
         }
       }
+
       /*"filtered elements of an array" in {
 
       }*/
@@ -161,6 +176,20 @@ class JsonLensesSpec extends Specification with SpecHelpers {
       "set element of array" in {
         """["a", "b", 2, 5, 8, 3]""" update (element(3) ! set(35)) must be_json( """["a", "b", 2, 35, 8, 3]""")
       }
+      "orSingletonArray" in {
+        "empty JsArray" in {
+          "[]".update(arrayOrSingletonAsArray ! set(Seq(1, 2, 3, 4, 5))) must be_json("""[1, 2, 3, 4, 5]""")
+        }
+        "filled JsArray" in {
+          "[1,2,3,4,5]".update(arrayOrSingletonAsArray / * ! modify[Int](_ + 1)) must be_json("""[2, 3, 4, 5, 6]""")
+        }
+        "single int value" in {
+          "5".update(arrayOrSingletonAsArray / * ! modify[Int](_ + 1)) must be_json("""[6]""")
+        }
+        "single object value" in {
+          """{ "a": 5 }""".update(arrayOrSingletonAsArray / * / 'a ! modify[Int](_ + 1)) must be_json("""[{ "a" : 6 }]""")
+        }
+      }
       "change a found element" in {
         "in a homogenuous array" in {
           "if found" in {
diff --git a/src/test/scala/spray/json/lenses/JsonPathExamplesSpec.scala b/src/test/scala/spray/json/lenses/JsonPathExamplesSpec.scala
index 707671b..0b43039 100644
--- a/src/test/scala/spray/json/lenses/JsonPathExamplesSpec.scala
+++ b/src/test/scala/spray/json/lenses/JsonPathExamplesSpec.scala
@@ -38,6 +38,24 @@ class JsonPathExamplesSpec extends Specification with SpecHelpers {
       |}
     """.stripMargin)
 
+  val singleElemArray = JsonParser(
+    """
+      |{ "store": {
+      |    "book":
+      |      { "category": "reference",
+      |        "author": "Nigel Rees",
+      |        "title": "Sayings of the Century",
+      |        "price": 8.95
+      |      }
+      |    ,
+      |    "bicycle": {
+      |      "color": "red",
+      |      "price": 19.95
+      |    }
+      |  }
+      |}
+    """.stripMargin)
+
   "Examples" should {
     "with Scala syntax" in {
       "All authors" in {
@@ -46,6 +64,9 @@ class JsonPathExamplesSpec extends Specification with SpecHelpers {
       "Author of first book" in {
         json.extract[String](("store" / "book" / element(0) / "author")) must be_==("Nigel Rees")
       }
+      "Author of first book no array" in {
+        singleElemArray.extract[String](("store" / "book" / arrayOrSingletonAsArray / element(0) / "author")) must be_==("Nigel Rees")
+      }
       "Books with category 'reference'" in {
         json.extract[String](("store" / "book" / filter("category".is[String](_ == "reference")) / "title")) must be_==(Seq("Sayings of the Century"))
       }