Pipes, Guards & Interceptors

Preview — 3 of 10 questions

In NestJS, what is the primary purpose of a pipe?

javascript

import { Controller, Get, Param, ParseIntPipe } from '@nestjs/common';

@Controller('users')
export class UsersController {
  @Get(':id')
  findOne(@Param('id', ParseIntPipe) id: number): string {
    return `user ${id}`; // id is already a number
  }
}

ATo authorize requests by returning true or false

BTo catch and format exceptions

CTo transform or validate input data before it reaches the handler

DTo log requests and responses

Which built-in pipe converts a string route parameter into a number, throwing if it isn't numeric?

javascript

import { Controller, Get, Query, ParseIntPipe } from '@nestjs/common';

@Controller('items')
export class ItemsController {
  @Get()
  list(@Query('page', ParseIntPipe) page: number): string {
    return `page ${page}`; // "3" -> 3
  }
}

ADefaultValuePipe

BParseBoolPipe

CValidationPipe

DParseIntPipe

A query param limit is optional, and you want it to default to 20 and still be parsed as an integer. Which pipe ordering works?

javascript

import { Controller, Get, Query, DefaultValuePipe, ParseIntPipe } from '@nestjs/common';

@Controller('items')
export class ItemsController {
  @Get()
  list(@Query('limit', new DefaultValuePipe(20), ParseIntPipe) limit: number): string {
    return `limit ${limit}`;
  }
}

A@Query('limit', ParseIntPipe, new DefaultValuePipe(20))

B@Query('limit', ParseIntPipe) only

C@Query('limit', new DefaultValuePipe(20)) only

D@Query('limit', new DefaultValuePipe(20), ParseIntPipe)

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