fix: accessing optional properties through reflection (#204)

CHANGELOG.md

@@ -20,6 +20,7 @@
 - Fixed checking dictionary values for nil in `default` filter
 - Fixed comparing string variables with string literals, in Swift 4 string literals became `Substring` and thus couldn't be directly compared to strings.
 - Integer literals now resolve into Int values, not Float
+- Fixed accessing properties of optional properties via reflection
 
 
 ## 0.10.1

Sources/Variable.swift

@@ -187,11 +187,33 @@ extension Mirror {
     if result == nil {
       // go through inheritance chain to reach superclass properties
       return superclassMirror?.getValue(for: key)
-    } else if let result = result, String(describing: result) == "nil" {
+    } else if let result = result {
-      // mirror returns non-nil value even for nil-containing properties
+      guard String(describing: result) != "nil" else {
-      // so we have to check if its value is actually nil or not
+        // mirror returns non-nil value even for nil-containing properties
-      return nil
+        // so we have to check if its value is actually nil or not
+        return nil
+      }
+      if let result = (result as? AnyOptional)?.wrapped {
+        return result
+      } else {
+        return result
+      }
     }
     return result
   }
 }
+
+protocol AnyOptional {
+  var wrapped: Any? { get }
+}
+
+extension Optional: AnyOptional {
+  var wrapped: Any? {
+    switch self {
+    case let .some(value): return value
+    case .none: return nil
+    }
+  }
+}
+
+

Tests/StencilTests/VariableSpec.swift

@@ -26,6 +26,7 @@ fileprivate class WebSite {
 
 fileprivate class Blog: WebSite {
   let articles: [Article] = [Article(author: Person(name: "Kyle"))]
+  let featuring: Article? = Article(author: Person(name: "Jhon"))
 }
 
 func testVariable() {
@@ -160,5 +161,11 @@ func testVariable() {
       try expect(result) == "blog.com"
     }
 
+    $0.it("can resolve optional variable property using reflection") {
+      let variable = Variable("blog.featuring.author.name")
+      let result = try variable.resolve(context) as? String
+      try expect(result) == "Jhon"
+    }
+
   }
 }