Swagger Setup

OpenAPI is a standard JSON/YAML description of a REST API. Swagger UI turns it into an interactive page where frontend developers and testers can try every endpoint.

npm i @nestjs/swagger

added 3 packages in 3s

src/main.ts

import { NestFactory } from '@nestjs/core';
import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  const config = new DocumentBuilder()
    .setTitle('ShopEase API')
    .setDescription('Products, cart, orders and payments for the ShopEase storefront')
    .setVersion('1.0')
    .addBearerAuth()
    .addServer('http://localhost:3000', 'Local')
    .addServer('https://api.shopease.in', 'Production')
    .build();
  const documentFactory = () => SwaggerModule.createDocument(app, config);
  SwaggerModule.setup('docs', app, documentFactory, {
    jsonDocumentUrl: 'docs/json',
    swaggerOptions: { persistAuthorization: true },
  });

  await app.listen(3000);
}
bootstrap();

curl -s http://localhost:3000/docs/json | head -c 300

{"openapi":"3.0.0","paths":{"/products":{"get":{"operationId":"ProductsController_findAll","parameters":[{"name":"category","required":false,"in":"query","schema":{"type":"string"}}],"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"array",...

Without help, Swagger cannot see TypeScript types at runtime. The Nest CLI plugin reads your DTOs at compile time and adds @ApiProperty() for you (including optional fields and class-validator rules).

{
  "collection": "@nestjs/schematics",
  "sourceRoot": "src",
  "compilerOptions": {
    "plugins": [
      { "name": "@nestjs/swagger", "options": { "classValidatorShim": true, "introspectComments": true } }
    ]
  }
}