Interceptor interface in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Interceptor interface from NestJS.

NestJS

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

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AModule

BController

CNestInterceptor

DInjectable

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Controller instead of NestInterceptor

Using Injectable instead of NestInterceptor

Forgetting to import NestInterceptor

The NestInterceptor interface is imported from @nestjs/common to create interceptors.

2fill in blank

medium

Complete the code to implement the Interceptor interface in a class.

NestJS

export class LoggingInterceptor implements [1] { }

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APipeTransform

BNestInterceptor

CExceptionFilter

DGuard

Attempts:

3 left

💡 Hint

Common Mistakes

Implementing PipeTransform instead of NestInterceptor

Implementing Guard or ExceptionFilter by mistake

To create an interceptor, the class must implement the NestInterceptor interface.

3fill in blank

hard

Fix the error in the intercept method signature by completing the parameter type.

NestJS

intercept(context: [1], next: CallHandler): Observable<any> { return next.handle(); }

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AResponse

BHttpContext

CRequest

DExecutionContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using Request or Response instead of ExecutionContext

Using a non-existent HttpContext type

The intercept method receives an ExecutionContext parameter to access details about the current request.

4fill in blank

hard

Fill both blanks to correctly import and use CallHandler in the interceptor.

NestJS

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

intercept(context: ExecutionContext, next: [2]): Observable<any> {
  return next.handle();
}

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AExecutionContext

BCallHandler

CObservable

DNestInterceptor

Attempts:

3 left

💡 Hint

Common Mistakes

Importing wrong types or missing CallHandler

Using wrong parameter types in intercept method

ExecutionContext and CallHandler are both imported from @nestjs/common and used in the intercept method.

5fill in blank

hard

Fill all three blanks to create a basic interceptor that logs before and after the request.

NestJS

import { Injectable, [1], ExecutionContext, CallHandler } from '@nestjs/common';
import { [2] } from 'rxjs';
import { tap } from 'rxjs/operators';

@Injectable()
export class LoggingInterceptor implements [3] {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    console.log('Before...');
    const now = Date.now();
    return next.handle().pipe(
      tap(() => console.log(`After... ${Date.now() - now}ms`))
    );
  }
}

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AInjectable

Btap

CNestInterceptor

DObservable

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing tap operator with Observable type

Forgetting to add @Injectable decorator

Not implementing NestInterceptor interface

The interceptor class is decorated with @Injectable(), implements NestInterceptor, and uses Observable from rxjs.