How do you use an interceptor to transform every response into a standard envelope format in NestJS?

Q: How do you use an interceptor to transform every response into a standard envelope format in NestJS?

export interface ApiResponse { data: T; timestamp: string; statusCode: number; } @Injectable() export class TransformInterceptor implements NestInterceptor > { intercept(ctx: ExecutionContext, next: CallHandler): Observable > { const statusCode = ctx.switchToHttp().getResponse().statusCode; return next.handle().pipe( map(data => ({ data, timestamp: new Date().toISOString(), statusCode, })), ); } } // Before: { id: 1, name: 'Alice' } // After: { data: { id: 1, name: 'Alice' }, timestamp: '2024-01-01T...', statusCode: 200 } app.useGlobalInterceptors(new TransformInterceptor()) — no DI support. { provide: APP_INTERCEPTOR, useClass: TransformInterceptor } — full DI support, preferred. The map() operator transforms every emitted value from the handler's observable. null and undefined handler returns are also passed through map() — handle them if needed.

Difficulty: 5/10

interceptors, global providers, response formatting

Implement NestInterceptor with a generic type, use map() in the RxJS pipeline to wrap every handler return value in a standard object. Register globally via APP_INTERCEPTOR or app.useGlobalInterceptors() so every endpoint returns the same shape.

Response transform interceptor

Global registration options:

1
app.useGlobalInterceptors(new TransformInterceptor()) — no DI support.
2
{ provide: APP_INTERCEPTOR, useClass: TransformInterceptor } — full DI support, preferred.
3

How do you use an interceptor to transform every response into a standard envelope format in NestJS?

Difficulty: 5/10

interceptors, global providers, response formatting

Implement NestInterceptor with a generic type, use map() in the RxJS pipeline to wrap every handler return value in a standard object. Register globally via APP_INTERCEPTOR or app.useGlobalInterceptors() so every endpoint returns the same shape.

Response transform interceptor

Global registration options:

1
app.useGlobalInterceptors(new TransformInterceptor()) — no DI support.
2
{ provide: APP_INTERCEPTOR, useClass: TransformInterceptor } — full DI support, preferred.
3

How do you use an interceptor to transform every response into a standard envelope format in NestJS?

Implement NestInterceptor with a generic type, use map() in the RxJS pipeline to wrap every handler return value in a standard object. Register globally via APP_INTERCEPTOR or app.useGlobalInterceptors() so every endpoint returns the same shape.

How do you use an interceptor to transform every response into a standard envelope format in NestJS?

Implement NestInterceptor with a generic type, use map() in the RxJS pipeline to wrap every handler return value in a standard object. Register globally via APP_INTERCEPTOR or app.useGlobalInterceptors() so every endpoint returns the same shape.

Scenario Questions

Follow-up Questions