Add type safe render method

.travis.yml

@@ -10,28 +10,21 @@ branches:
 
 matrix:
   include:
-    - os: linux
-      dist: trusty
-      sudo: required
-      env: SWIFT_SNAPSHOT=3.1.1
     - os: linux
       dist: trusty
       sudo: required
       env: SWIFT_SNAPSHOT=4.0.3
     - os: linux
       dist: trusty
       sudo: required
-    - os: osx
-      osx_image: xcode8.3
-      sudo: required
-      env: SWIFT_SNAPSHOT=3.1.1
     - os: osx
       osx_image: xcode9.2
       sudo: required
       env: SWIFT_SNAPSHOT=4.0.3
     - os: osx
-      osx_image: xcode9.3beta
+      osx_image: xcode9.3
       sudo: required
+      env: SWIFT_SNAPSHOT:4.1
 
 before_install:
   - git clone https://github.com/IBM-Swift/Package-Builder.git

Package.swift

@@ -1,3 +1,6 @@
+// swift-tools-version:4.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
 /**
  * Copyright IBM Corporation 2016, 2018
  *
@@ -18,8 +21,24 @@ import PackageDescription
 
 let package = Package(
     name: "KituraStencil",
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "KituraStencil",
+            targets: ["KituraStencil"]
+        )
+    ],
     dependencies: [
-        .Package(url: "https://github.com/IBM-Swift/Kitura-TemplateEngine.git", majorVersion: 1, minor: 7),
-        .Package(url: "https://github.com/kylef/Stencil.git", majorVersion: 0, minor: 10)
+        .package(url: "https://github.com/IBM-Swift/Kitura-TemplateEngine.git", from: "2.0.0"),
+        .package(url: "https://github.com/kylef/Stencil.git", .upToNextMinor(from: "0.11.0"))
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
+        .target(
+            name: "KituraStencil",
+            dependencies: ["KituraTemplateEngine", "Stencil"]
+        )
     ]
 )
+

Sources/KituraStencil/KituraStencilTemplateEngine.swift

@@ -17,10 +17,27 @@
 import KituraTemplateEngine
 import Stencil
 import PathKit
+import Foundation
 
+// StencilTemplateEngineError for Error handling.
 public enum StencilTemplateEngineError: Swift.Error {
+    // Thrown when StencilTemplateEngine.rootPaths property is empty.
     case rootPathsEmpty
-    case deprecatedRenderMethodCalled // call render(filePath, context, options, templateName)
+
+    // Call render(filePath, context, options, templateName).
+    case deprecatedRenderMethodCalled
+
+    // Thrown when unable to cast 'json' value to a [String: Any].
+    case unableToCastJSONToDict
+
+    // Thrown when unable to encode the Encodable value provided to data.
+    case unableToEncodeValue(value: Encodable)
+
+    // Thrown when Stencil fails to render the context with the given template.
+    case unableToRenderContext(context: [String: Any])
+
+    //Thrown when an array or set of Encodables is passed without a Key.
+    case noKeyProvidedForType(value: Encodable)
 }
 
 public class StencilTemplateEngine: TemplateEngine {
@@ -39,7 +56,7 @@ public class StencilTemplateEngine: TemplateEngine {
     public func render(filePath: String, context: [String: Any]) throws -> String {
         throw StencilTemplateEngineError.deprecatedRenderMethodCalled
     }
-
+    
     public func render(filePath: String, context: [String: Any], options: RenderingOptions,
                        templateName: String) throws -> String {
         if rootPaths.isEmpty {
@@ -50,6 +67,46 @@ public class StencilTemplateEngine: TemplateEngine {
         let environment = Environment(loader: loader, extensions: [`extension`])
         var context = context
         context["loader"] = loader
-        return try environment.renderTemplate(name: templateName,  context: context)
+        do {
+            return try environment.renderTemplate(name: templateName,  context: context)
+        } catch {
+            throw StencilTemplateEngineError.unableToRenderContext(context: context)
+        }
+    }
+
+    public func render<T: Encodable>(filePath: String, with value: T, forKey key: String?,
+                                   options: RenderingOptions, templateName: String) throws -> String {
+        if rootPaths.isEmpty {
+            throw StencilTemplateEngineError.rootPathsEmpty
+        }
+
+        //Throw an error if an array is passed without providing a key.
+        if key == nil {
+            let mirror = Mirror(reflecting: value)
+            if mirror.displayStyle == .collection || mirror.displayStyle == .set {
+                throw StencilTemplateEngineError.noKeyProvidedForType(value: value)
+            }
+        }
+
+        let json: [String: Any]
+
+        if let contextKey = key {
+            json = [contextKey: value]
+        } else {
+            var data = Data()
+            do {
+                data = try JSONEncoder().encode(value)
+            } catch {
+                throw StencilTemplateEngineError.unableToEncodeValue(value: value)
+            }
+
+            guard let dict = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any] else {
+                throw StencilTemplateEngineError.unableToCastJSONToDict
+            }
+
+            json = dict
+        }
+
+        return try render(filePath: filePath, context: json, options: options, templateName: templateName)
     }
 }