Catch decorator in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Catch decorator from NestJS.

NestJS

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

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ACatch

BInjectable

CController

DModule

Attempts:

3 left

💡 Hint

Common Mistakes

Importing the wrong decorator like Controller or Injectable.

Forgetting to import the Catch decorator.

The Catch decorator is imported from @nestjs/common to create exception filters.

2fill in blank

medium

Complete the code to apply the Catch decorator to an exception filter class.

NestJS

@[1]() 
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: any, host: ArgumentsHost) {
    // handle exception
  }
}

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AModule

BCatch

CController

DInjectable

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Injectable instead of @Catch.

Not adding parentheses after the decorator.

The @Catch() decorator marks a class as an exception filter in NestJS.

3fill in blank

hard

Fix the error in the Catch decorator usage to catch only HttpException errors.

NestJS

@Catch([1])
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    // handle HttpException
  }
}

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AArgumentsHost

BError

CExceptionFilter

DHttpException

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the wrong class like Error or ArgumentsHost.

Not passing any argument when wanting to catch specific exceptions.

The @Catch() decorator can take exception types as arguments to catch specific exceptions like HttpException.

4fill in blank

hard

Fill both blanks to extract the response object and send a JSON error message inside the catch method.

NestJS

catch(exception: HttpException, host: ArgumentsHost) {
  const ctx = host.[1]();
  const response = ctx.[2]();
  response.status(exception.getStatus()).json({
    statusCode: exception.getStatus(),
    message: exception.message
  });
}

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AswitchToHttp

BgetResponse

CgetRequest

Dhandle

Attempts:

3 left

💡 Hint

Common Mistakes

Using getRequest instead of getResponse for sending response.

Not switching to HTTP context before getting response.

Use host.switchToHttp() to get the HTTP context, then ctx.getResponse() to get the response object.

5fill in blank

hard

Fill the blanks to create a Catch decorator that catches both HttpException and QueryFailedError exceptions.

NestJS

@Catch([1], [2])
export class DatabaseExceptionFilter implements ExceptionFilter {
  catch(exception: any, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse();
    response.status(500).json({
      statusCode: 500,
      error: exception.message
    });
  }
}

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AHttpException

BQueryFailedError

CExceptionFilter

DArgumentsHost

Attempts:

3 left

💡 Hint

Common Mistakes

Passing non-exception classes.

Not passing multiple exceptions when needed.

The @Catch() decorator can take multiple exception classes to catch. Here, HttpException and QueryFailedError are caught.