feat(common): allow to serialize plain object

packages/common/serializer/class-serializer.interceptor.ts

@@ -1,3 +1,4 @@
+import { ClassSerializerContextOptions } from './class-serializer.interfaces';
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 import { Inject, Injectable, Optional } from '../decorators/core';
@@ -63,7 +64,7 @@ export class ClassSerializerInterceptor implements NestInterceptor {
    */
   serialize(
     response: PlainLiteralObject | Array<PlainLiteralObject>,
-    options: ClassTransformOptions,
+    options: ClassSerializerContextOptions,
   ): PlainLiteralObject | Array<PlainLiteralObject> {
     if (!isObject(response) || response instanceof StreamableFile) {
       return response;
@@ -76,16 +77,24 @@ export class ClassSerializerInterceptor implements NestInterceptor {
 
   transformToPlain(
     plainOrClass: any,
-    options: ClassTransformOptions,
+    options: ClassSerializerContextOptions,
   ): PlainLiteralObject {
-    return plainOrClass
-      ? classTransformer.classToPlain(plainOrClass, options)
-      : plainOrClass;
+    if (!plainOrClass) {
+      return plainOrClass;
+    }
+    if (!options.type) {
+      return classTransformer.classToPlain(plainOrClass, options);
+    }
+    if (plainOrClass instanceof options.type) {
+      return classTransformer.classToPlain(plainOrClass, options);
+    }
+    const instance = classTransformer.plainToClass(options.type, plainOrClass);
+    return classTransformer.classToPlain(instance, options);
   }
 
   protected getContextOptions(
     context: ExecutionContext,
-  ): ClassTransformOptions | undefined {
+  ): ClassSerializerContextOptions | undefined {
     return this.reflector.getAllAndOverride(CLASS_SERIALIZER_OPTIONS, [
       context.getHandler(),
       context.getClass(),

packages/common/serializer/class-serializer.interfaces.ts

@@ -0,0 +1,6 @@
+import { ClassTransformOptions } from '../interfaces/external/class-transform-options.interface';
+import { Type } from '../interfaces';
+
+export interface ClassSerializerContextOptions extends ClassTransformOptions {
+  type?: Type<any>;
+}

packages/common/serializer/decorators/serialize-options.decorator.ts

@@ -1,6 +1,6 @@
 import { SetMetadata } from '../../decorators';
-import { ClassTransformOptions } from '../../interfaces/external/class-transform-options.interface';
+import { ClassSerializerContextOptions } from '../class-serializer.interfaces';
 import { CLASS_SERIALIZER_OPTIONS } from '../class-serializer.constants';
 
-export const SerializeOptions = (options: ClassTransformOptions) =>
+export const SerializeOptions = (options: ClassSerializerContextOptions) =>
   SetMetadata(CLASS_SERIALIZER_OPTIONS, options);

packages/common/serializer/index.ts

@@ -1,2 +1,3 @@
 export * from './class-serializer.interceptor';
 export * from './decorators';
+export * from './class-serializer.interfaces';