How do you set up Swagger in a NestJS application and annotate your controllers?

Q: How do you set up Swagger in a NestJS application and annotate your controllers?

// main.ts import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger'; async function bootstrap() { const app = await NestFactory.create(AppModule); const config = new DocumentBuilder() .setTitle('Users API') .setDescription('REST API documentation') .setVersion('1.0') .addBearerAuth() .addTag('users') .build(); const document = SwaggerModule.createDocument(app, config); SwaggerModule.setup('api-docs', app, document); // /api-docs await app.listen(3000); } // Controller @ApiTags('users') @ApiBearerAuth() @Controller('users') export class UsersController { @ApiOperation({ summary: 'Find a user by ID' }) @ApiParam({ name: 'id', type: Number }) @ApiResponse({ status: 200, type: UserEntity, description: 'User found' }) @ApiResponse({ status: 404, description: 'User not found' }) @Get(':id') findOne(@Param('id', ParseIntPipe) id: number) {} } Install @nestjs/swagger and swagger-ui-express (or fastify-swagger for Fastify). @ApiTags() groups routes in the Swagger UI — apply at the controller level. @ApiOperation() documents what the route does — always add a summary. @ApiResponse() documents each possible response including error codes. NestJS infers types from TypeScript metadata — use @ApiProperty() for arrays and optional fields.

Difficulty: 5/10

Swagger integration, NestJS decorators, API documentation

Install @nestjs/swagger and swagger-ui-express. Use DocumentBuilder to configure the spec metadata and SwaggerModule.createDocument() to generate the spec. Call SwaggerModule.setup() to mount the Swagger UI at a path. Annotate controllers with @ApiTags(), handlers with @ApiOperation() and @ApiResponse(), and params with @ApiParam().

Swagger setup in main.ts and controller annotations

Swagger setup checklist:

1
Install @nestjs/swagger and swagger-ui-express (or fastify-swagger for Fastify).
2

How do you set up Swagger in a NestJS application and annotate your controllers?

Difficulty: 5/10

Swagger integration, NestJS decorators, API documentation

Install @nestjs/swagger and swagger-ui-express. Use DocumentBuilder to configure the spec metadata and SwaggerModule.createDocument() to generate the spec. Call SwaggerModule.setup() to mount the Swagger UI at a path. Annotate controllers with @ApiTags(), handlers with @ApiOperation() and @ApiResponse(), and params with @ApiParam().

Swagger setup in main.ts and controller annotations

Swagger setup checklist:

1
Install @nestjs/swagger and swagger-ui-express (or fastify-swagger for Fastify).
2

How do you set up Swagger in a NestJS application and annotate your controllers?

How do you set up Swagger in a NestJS application and annotate your controllers?

Scenario Questions

Follow-up Questions