File validation pipe in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the correct decorator for file upload in NestJS.

NestJS

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

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AUploadedFile

BUseInterceptors

CController

DGet

Attempts:

3 left

💡 Hint

Common Mistakes

Using @UseInterceptors instead of @UploadedFile

Importing from wrong package

Confusing with @Controller or @Get decorators

The @UploadedFile() decorator is used to access the uploaded file in a controller method.

2fill in blank

medium

Complete the code to apply a file validation pipe in the controller method parameter.

NestJS

uploadFile(@UploadedFile(new [1]()) file: Express.Multer.File) { return file; }

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AFileValidationPipe

BValidationPipe

CParseFilePipe

DParseIntPipe

Attempts:

3 left

💡 Hint

Common Mistakes

Using ValidationPipe which does not handle files

Using a non-existent FileValidationPipe

Using ParseIntPipe which is for numbers

The ParseFilePipe is the built-in NestJS pipe for validating uploaded files.

3fill in blank

hard

Fix the error in the pipe options to allow only PNG files.

NestJS

new ParseFilePipe({ validators: [ new FileTypeValidator({ fileType: '[1]' }) ] })

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Aimage/jpeg

Bimage/png

Capplication/pdf

Dtext/plain

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'image/jpeg' which allows JPEG files

Using 'application/pdf' which allows PDFs

Using 'text/plain' which allows text files

The FileTypeValidator expects the MIME type string. For PNG files, it is image/png.

4fill in blank

hard

Fill both blanks to set a max file size of 1MB and allow only JPEG files.

NestJS

new ParseFilePipe({ validators: [ new FileTypeValidator({ fileType: '[1]' }), new MaxFileSizeValidator({ maxSize: [2] }) ] })

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Aimage/jpeg

B1048576

Cimage/png

D2097152

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'image/png' instead of 'image/jpeg'

Setting maxSize to 2097152 which is 2MB

JPEG files have MIME type image/jpeg. 1MB in bytes is 1048576.

5fill in blank

hard

Fill all three blanks to create a custom validation pipe that checks file size and type.

NestJS

export class CustomFileValidationPipe implements PipeTransform {
  transform(file: Express.Multer.File) {
    if (!file) throw new BadRequestException('No file uploaded');
    if (file.mimetype !== '[1]') throw new BadRequestException('Invalid file type');
    if (file.size > [2]) throw new BadRequestException('File too large');
    return file;
  }
}

// Usage: @UploadedFile(new [3]())

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Aimage/png

B1048576

CCustomFileValidationPipe

Dimage/jpeg

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'image/png' instead of 'image/jpeg'

Using wrong max size value

Not using the custom pipe class name in the decorator

The custom pipe checks for JPEG files (image/jpeg) and max size 1MB (1048576 bytes). It is used by passing its class name.