Pipe binding (parameter, method, controller, global) in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to bind a pipe to a single parameter in a NestJS controller method.

NestJS

async getUser(@Param('id', [1]) id: number) { return this.userService.findById(id); }

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Aid

BParseIntPipe

CBody

DQuery

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting 'id' (the parameter name) instead of a pipe like ParseIntPipe

Confusing pipes with other decorators like @Body or @Query

To bind a pipe to a single parameter, provide the pipe class as the second argument to the @Param decorator, such as ParseIntPipe to convert the string ID to a number.

2fill in blank

medium

Complete the code to apply a pipe to an entire controller method.

NestJS

@UsePipes([1])
async create(@Body() data: CreateDto) { return this.service.create(data); }

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AController

BParseIntPipe

CHttpException

DValidationPipe

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class that is not a pipe inside @UsePipes

Confusing @UsePipes with @UseGuards or other decorators

UsePipes decorator applies the specified pipe(s) to the whole method; ValidationPipe is commonly used for DTO validation.

3fill in blank

hard

Fix the error in binding a pipe globally in the main.ts file.

NestJS

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalPipes(new [1]());
  await app.listen(3000);
}

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AValidationPipe

BParseIntPipe

CHttpException

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-pipe classes like Controller or HttpException

Forgetting to instantiate the pipe with 'new'

ValidationPipe is the correct pipe to use globally for validating all incoming requests.

4fill in blank

hard

Fill both blanks to bind a pipe to a controller and a method.

NestJS

@UsePipes([1])
@Controller('items')
export class ItemsController {
  @UsePipes([2])
  async update(@Param('id', ParseIntPipe) id: number) {
    return this.itemsService.update(id);
  }
}

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AValidationPipe

BParseIntPipe

CHttpException

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-pipe classes in @UsePipes

Mixing up controller and method pipe usage

ValidationPipe is applied at the controller level for general validation; ParseIntPipe is applied at the method level to parse the 'id' parameter.

5fill in blank

hard

Fill all three blanks to create a custom pipe and bind it globally.

NestJS

import { PipeTransform, Injectable, ArgumentMetadata } from '@nestjs/common';

@Injectable()
export class [1] implements PipeTransform {
  transform(value: any, metadata: ArgumentMetadata) {
    if (!value) {
      throw new [2]('Value is required');
    }
    return value.trim();
  }
}

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useGlobalPipes(new [3]());
  await app.listen(3000);
}

Drag options to blanks, or click blank then click option'

ATrimPipe

BBadRequestException

DValidationPipe

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong exception class

Not instantiating the pipe with 'new' when binding globally

Mismatching class names

TrimPipe is the custom pipe class name; BadRequestException is thrown on invalid input; the global pipe instance is created with new TrimPipe().