feat(JsonView): add JsonView decorator to expose object properties

Author: snirs90

src/decorators.ts

@@ -1,3 +1,4 @@
+import { ClassTransformer } from './ClassTransformer';
 import {defaultMetadataStorage} from "./storage";
 import {TypeMetadata} from "./metadata/TypeMetadata";
 import {ExposeMetadata} from "./metadata/ExposeMetadata";
@@ -48,4 +49,30 @@ export function Exclude(options?: ExcludeOptions) {
         const metadata = new ExcludeMetadata(object instanceof Function ? object : object.constructor, propertyName, options || {});
         defaultMetadataStorage.addExcludeMetadata(metadata);
     };
+}
+
+/**
+ * Return the object with the exposed properties only.
+ */
+export function JsonView(params: {}, method?: string): Function {
+
+    return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
+        const classTransformer: any = new ClassTransformer();
+        const originalMethod = descriptor.value;
+
+        descriptor.value = function(...args: any[]) {
+            let result: any = originalMethod.apply(this, args);
+
+            let transformer: Function;
+            if (typeof method === 'string' && method) {
+                transformer = classTransformer[method];
+            }
+            else {
+                transformer = classTransformer.classToPlain;
+            }
+
+            result = transformer(result, params);
+            return result;
+        }
+    }
 }