Vatsalya-singhi

Vatsalya-singhi

import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';
import * as Joi from 'joi';

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true, // Makes config available across the app
      envFilePath: `.env.${process.env.NODE_ENV || 'development'}`, // Load specific .env file based on NODE_ENV
      ignoreEnvFile: process.env.NODE_ENV === 'production', // Ignore .env in production (use external env variables)

Vatsalya-singhi

// accessing env variables securely
import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

@Injectable()
export class AppService {
  constructor(private configService: ConfigService) {}

  getDatabaseUrl(): string {
    return this.configService.get<string>('DATABASE_URL');

Vatsalya-singhi

// app.module.ts
import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';

@Module({
  // loads default .env file present in project directory
  imports: [ConfigModule.forRoot()],
})
export class AppModule {}

Vatsalya-singhi

import { Injectable, NestInterceptor, ExecutionContext, CallHandler, HttpException, HttpStatus } from '@nestjs/common';
import { Observable } from 'rxjs';
import { catchError } from 'rxjs/operators';

@Injectable()
export class ErrorHandlingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    return next.handle().pipe(
      catchError(err => {
        throw new HttpException('Something went wrong', HttpStatus.INTERNAL_SERVER_ERROR);

Vatsalya-singhi

import { Controller, Get, UseInterceptors } from '@nestjs/common';
import { LoggingInterceptor } from './logging.interceptor';
import { TransformInterceptor } from './transform.interceptor';

@Controller('users')
@UseInterceptors(LoggingInterceptor, TransformInterceptor) //applying multiple interceptors
export class UsersController {
  @Get()
  findAll() {
    return { name: 'John Doe', age: 30 };

Vatsalya-singhi

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable()
export class TransformInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    return next.handle().pipe(
      map(data => ({
        success: true,

Vatsalya-singhi

// app.module.ts
import { Module } from '@nestjs/common';
import { APP_INTERCEPTOR } from '@nestjs/core';
import { LoggingInterceptor } from './logging.interceptor';

@Module({
  providers: [
    {
      provide: APP_INTERCEPTOR,
      useClass: LoggingInterceptor,

Vatsalya-singhi

// main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { LoggingInterceptor } from './logging.interceptor';
import { APP_INTERCEPTOR } from '@nestjs/core';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalInterceptors(new LoggingInterceptor()); // Apply globally
  await app.listen(3000);

Vatsalya-singhi

import { Controller, Get, UseInterceptors } from '@nestjs/common';
import { LoggingInterceptor } from './logging.interceptor';

@Controller('users')
@UseInterceptors(LoggingInterceptor) // Apply to all routes in this controller
export class UsersController {
  @Get()
  findAll() {
    return { message: 'List of users' };
  }