NestJS code explainers

typescript

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

Validating env config at boot in NestJS

configuration schema-validation environment-variables

Intermediate 8 steps

typescript

import { Inject, Injectable, Logger } from '@nestjs/common';
import { CACHE_MANAGER } from '@nestjs/cache-manager';
import { Cache } from 'cache-manager';
import { InjectRepository } from '@nestjs/typeorm';

A cache-aside country lookup in NestJS

cache-aside dependency-injection batch-lookup

Intermediate 8 steps

typescript

import { Injectable, Scope, Inject, NotFoundException } from '@nestjs/common';
import { REQUEST } from '@nestjs/core';
import { Request } from 'express';
import { DataSource } from 'typeorm';

Per-tenant database connections in NestJS

multi-tenancy connection-pooling dependency-injection

Advanced 8 steps

typescript

import {
  CallHandler,
  ConflictException,
  ExecutionContext,

Idempotent POST requests in NestJS with Redis

idempotency interceptor redis

Advanced 7 steps

typescript

import { Injectable, Scope } from '@nestjs/common';
import DataLoader from 'dataloader';
import { InjectRepository } from '@nestjs/typeorm';
import { In, Repository } from 'typeorm';

Batching queries with DataLoader in NestJS

dataloader batching n+1

Intermediate 7 steps

typescript

import {
  createParamDecorator,
  ExecutionContext,
  UnauthorizedException,

A signed-cookie param decorator in NestJS

custom-decorators hmac timing-safe-comparison

Advanced 8 steps

typescript

import {
  CallHandler,
  ExecutionContext,
  Injectable,

Deduping in-flight requests in NestJS

interceptor request-deduplication rxjs

Advanced 6 steps

typescript

import {
  Controller,
  Get,
  Param,

HTTP conditional caching in a NestJS controller

http-caching etag conditional-requests

Intermediate 7 steps

typescript

import {
  MiddlewareConsumer,
  Module,
  NestModule,

How middleware binds to routes in NestJS

middleware routing modules

Intermediate 6 steps

typescript

import { Injectable, UnauthorizedException } from '@nestjs/common';
import { PassportStrategy } from '@nestjs/passport';
import { Strategy } from 'passport-headerapikey';
import { ConfigService } from '@nestjs/config';

Building an API-key auth strategy in NestJS

authentication passport dependency-injection

Intermediate 8 steps

typescript

import { Type, applyDecorators } from '@nestjs/common';
import {
  ApiExtraModels,
  ApiOkResponse,

A reusable paginated Swagger decorator in NestJS

decorators generics openapi

Intermediate 6 steps

typescript

import {
  IsEmail,
  IsNotEmpty,
  IsOptional,

How validation groups reuse one DTO in NestJS

validation dto decorators

Intermediate 9 steps

typescript

import { Body, Controller, Ip, Post, UnauthorizedException } from '@nestjs/common';
import { Throttle, ThrottlerGuard } from '@nestjs/throttler';
import { UseGuards } from '@nestjs/common';
import { AuthService } from './auth.service';

Rate-limiting an auth flow in NestJS

rate-limiting authentication guards

Intermediate 8 steps

typescript

import { Controller, Param, Sse, MessageEvent } from '@nestjs/common';
import { Observable, interval, merge } from 'rxjs';
import { filter, map, takeWhile } from 'rxjs/operators';
import { JobService } from './job.service';

Streaming job progress with SSE in NestJS

server-sent-events reactive-streams rxjs

Intermediate 8 steps

typescript

import {
  Controller,
  All,
  Req,

Catch-all routes and error shaping in NestJS

exception-handling routing middleware

Intermediate 6 steps

typescript

import {
  ArgumentsHost,
  Catch,
  ConflictException,

Turning TypeORM lock errors into 409s in NestJS

exception-handling optimistic-locking http-status

Intermediate 6 steps

typescript

import {
  Injectable,
  PipeTransform,
  ArgumentMetadata,

A custom validation pipe in NestJS

validation dto recursion

Intermediate 10 steps

typescript

import {
  CallHandler,
  ExecutionContext,
  Injectable,

Recording HTTP metrics with a NestJS interceptor

interceptor observability prometheus

Intermediate 5 steps