DTO class creation in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a basic DTO class with a single string property.

NestJS

export class CreateUserDto {
  [1] name: string;
}

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

Apublic

Bname

Creadonly

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'private' or 'public' instead of 'readonly' for DTO properties.

Omitting any keyword and making the property mutable.

The readonly keyword is used in DTO classes to make properties immutable after creation, which is a common pattern in NestJS DTOs.

2fill in blank

medium

Complete the code to import the class-validator decorator for string validation.

NestJS

import { [1] } from 'class-validator';

export class CreateUserDto {
  readonly name: string;
}

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

AIsNumber

BIsDate

CIsBoolean

DIsString

Attempts:

3 left

💡 Hint

Common Mistakes

Using decorators for other types like numbers or booleans incorrectly.

Forgetting to import the decorator.

The IsString decorator validates that the property is a string, which is important for DTO input validation.

3fill in blank

hard

Fix the error in the DTO property decorator to validate a non-empty string.

NestJS

import { IsString, [1] } from 'class-validator';

export class CreateUserDto {
  @IsString()
  @[1]()
  readonly name: string;
}

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

AIsNotEmpty

BIsNumber

CIsOptional

DIsBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using IsOptional which allows empty values.

Using decorators for wrong types.

The IsNotEmpty decorator ensures the string is not empty, which is a common validation for required fields.

4fill in blank

hard

Fill both blanks to create a DTO class with a numeric age property that must be positive.

NestJS

import { IsPositive, [1] } from 'class-validator';

export class CreateUserDto {
  readonly name: string;
  @[2]()
  @IsPositive()
  readonly age: number;
}

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

AIsNumber

BIsString

CIsBoolean

DIsDate

Attempts:

3 left

💡 Hint

Common Mistakes

Using string or boolean decorators for numeric properties.

Forgetting to import the correct decorators.

The IsNumber decorator validates the property is a number, and IsPositive ensures it is greater than zero.

5fill in blank

hard

Fill all three blanks to create a DTO class with a required email string property validated for email format.

NestJS

import { IsString, [1], [2] } from 'class-validator';

export class CreateUserDto {
  @IsString()
  @IsEmail()
  @[3]()
  readonly email: string;
}

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

AIsEmail

BIsNotEmpty

CIsOptional

DIsBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using IsOptional which allows missing emails.

Using boolean decorators for string properties.

IsEmail validates the email format, and IsNotEmpty ensures the email is provided and not empty.