Timeout interceptor in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the correct NestJS module for interceptors.

NestJS

import { [1] } from '@nestjs/common';

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AInterceptor

BInjectable

CController

DModule

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Interceptor instead of @Injectable

Forgetting to import @Injectable

The @Injectable decorator is needed to mark the interceptor class as injectable by NestJS.

2fill in blank

medium

Complete the code to implement the NestJS interceptor interface.

NestJS

export class TimeoutInterceptor implements [1]<any> {

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ANestInterceptor

BCanActivate

CExceptionFilter

DPipeTransform

Attempts:

3 left

💡 Hint

Common Mistakes

Using PipeTransform instead of NestInterceptor

Confusing with ExceptionFilter

The NestInterceptor interface is implemented to create an interceptor in NestJS.

3fill in blank

hard

Fix the error in the method signature to correctly implement the intercept method.

NestJS

intercept(context: ExecutionContext, next: [1]): Observable<any> {

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AResponseHandler

BNextFunction

CRequestHandler

DCallHandler

Attempts:

3 left

💡 Hint

Common Mistakes

Using NextFunction which is from Express middleware

Using RequestHandler or ResponseHandler which do not exist in NestJS interceptors

The intercept method receives a CallHandler as the second argument to handle the request flow.

4fill in blank

hard

Fill in the blank to apply a timeout of 5000 milliseconds to the observable.

NestJS

return next.handle().pipe(timeout([1]));

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A5000

B3000

C10000

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 which disables timeout

Using too low or too high values not matching 5 seconds

The timeout operator takes the number of milliseconds before timing out. 5000 means 5 seconds.

5fill in blank

hard

Fill all three blanks to import the timeout operator, catchError operator, and throwError function from RxJS.

NestJS

import { [1], [2] } from 'rxjs/operators';
import { [3] } from 'rxjs';

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Atimeout

BcatchError

CthrowError

Dmap

Attempts:

3 left

💡 Hint

Common Mistakes

Including map instead of throwError

Missing catchError which handles errors

These three imports are needed to apply timeout, handle errors, and throw errors in rxjs streams.