Enable validation

src/main.ts

@@ -1,6 +1,7 @@
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
-import { Logger } from '@nestjs/common';
+import { BadRequestException, Logger, ValidationPipe } from '@nestjs/common';
+import { ValidationError } from 'class-validator';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
@@ -17,6 +18,31 @@ async function bootstrap() {
     credentials: true,
     origin,
   });
+  app.useGlobalPipes(
+    new ValidationPipe({
+      transform: true,
+      // https://stackoverflow.com/questions/75581669/customize-error-message-in-nest-js-using-class-validator
+      exceptionFactory: (validationErrors: ValidationError[] = []) => {
+        const errors = validationErrors.map((error) => ({
+          error: Object.values(error.constraints).join(', '),
+        }));
+
+        let errorMessage: string;
+        errors.forEach((value, index) => {
+          if (index == 0) {
+            errorMessage = value.error;
+          } else {
+            errorMessage = errorMessage.concat(', ', value.error);
+          }
+        });
+
+        return new BadRequestException({
+          status: 'Validation Error',
+          message: errorMessage,
+        });
+      },
+    }),
+  );
 
   await app.listen(process.env.PORT);
 }