add transform interceptor

src/main.ts

@@ -1,11 +1,13 @@
 import { ValidationPipe } from '@nestjs/common';
 import { NestFactory } from '@nestjs/core';
+import { TransformInterceptor } from 'src/transform.interceptor';
 import { AppModule } from './app.module';
 
 async function bootstrap() {
-  const app = await NestFactory.create(AppModule);
+    const app = await NestFactory.create(AppModule);
 
-  app.useGlobalPipes(new ValidationPipe());
-  await app.listen(3000);
+    app.useGlobalPipes(new ValidationPipe());
+    app.useGlobalInterceptors(new TransformInterceptor());
+    await app.listen(3000);
 }
 bootstrap();

src/transform.interceptor.ts

@@ -0,0 +1,15 @@
+import {
+    NestInterceptor,
+    ExecutionContext,
+    Injectable,
+    CallHandler,
+} from '@nestjs/common';
+import { classToPlain } from 'class-transformer';
+import { map } from 'rxjs/operators';
+
+@Injectable()
+export class TransformInterceptor implements NestInterceptor {
+    intercept(context: ExecutionContext, next: CallHandler<any>) {
+        return next.handle().pipe(map((data) => classToPlain(data)));
+    }
+}