feat: added empty string to null converter interceptor

apps/web-api/src/app.module.ts

@@ -37,6 +37,7 @@ import { PLEventsModule } from './pl-events/pl-events.module';
 import { OfficeHoursModule } from './office-hours/office-hours.module';
 import { MemberFollowUpsModule } from './member-follow-ups/member-follow-ups.module';
 import { MemberFeedbacksModule } from './member-feedbacks/member-feedbacks.module';
+import { EmptyStringToNullInterceptor } from './interceptors/empty-string-to-null.interceptor';
 
 @Module({
   controllers: [AppController],
@@ -104,6 +105,10 @@ import { MemberFeedbacksModule } from './member-feedbacks/member-feedbacks.modul
       provide: APP_INTERCEPTOR,
       useClass: ConcealEntityIDInterceptor,
     },
+    {
+      provide: APP_INTERCEPTOR,
+      useClass: EmptyStringToNullInterceptor
+    },
     {
       provide: APP_FILTER,
       useClass: LogException

apps/web-api/src/interceptors/empty-string-to-null.interceptor.ts

@@ -0,0 +1,35 @@
+import {
+  Injectable,
+  NestInterceptor,
+  ExecutionContext,
+  CallHandler
+} from '@nestjs/common';
+import { Observable } from 'rxjs';
+
+@Injectable()
+export class EmptyStringToNullInterceptor implements NestInterceptor {
+  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
+    const request = context.switchToHttp().getRequest();
+    const method = request.method;
+    if (method === 'POST' || method === 'PUT' || method === 'PATCH') {
+      request.body = this.convertEmptyStringsToNull(request.body);
+    }
+    return next.handle();
+  }
+
+  private convertEmptyStringsToNull(obj: any): any {
+    if (typeof obj === 'string') {
+      return obj === '' ? null : obj;
+    } else if (Array.isArray(obj)) {
+      return obj.map((item) => this.convertEmptyStringsToNull(item));
+    } else if (typeof obj === 'object' && obj !== null) {
+      const newObj: any = {};
+      for (const key of Object.keys(obj)) {
+        newObj[key] = this.convertEmptyStringsToNull(obj[key]);
+      }
+      return newObj;
+    }
+    return obj;
+  }
+}
+