HonestJS - Class Validator Pipe

A validation pipe for the HonestJS framework that automatically validates and transforms DTOs using class-validator and class-transformer.

Installation

bun add @honestjs/class-validator-pipe class-validator class-transformer
# or
pnpm add @honestjs/class-validator-pipe class-validator class-transformer
# or
npm install @honestjs/class-validator-pipe class-validator class-transformer

Basic Usage

1. Create a DTO class

import { IsEmail, IsString, MinLength, IsOptional } from 'class-validator'

export class CreateUserDto {
	@IsString()
	@MinLength(2)
	name: string

	@IsEmail()
	email: string

	@IsString()
	@IsOptional()
	bio?: string
}

2. Use the pipe in your application

import { Application } from 'honestjs'
import { ClassValidatorPipe } from '@honestjs/class-validator-pipe'

const { hono } = await Application.create(AppModule, {
	components: {
		pipes: [new ClassValidatorPipe()]
	}
})

Options

new ClassValidatorPipe({
	validator: { whitelist: true, forbidNonWhitelisted: false },
	transform: { enableImplicitConversion: true }
})

Validator options (defaults)

| Option | Default | Description | | ---------------------- | ------- | ----------------------------------------- | | whitelist | true | Strip properties not decorated in the DTO | | forbidNonWhitelisted | false | Throw when extra properties are sent |

Transform options (defaults)

| Option | Default | Description | | -------------------------- | ------- | -------------------------------------- | | enableImplicitConversion | true | Coerce string numbers to numbers, etc. |

Example: strict mode

new ClassValidatorPipe({ validator: { forbidNonWhitelisted: true } })

Recipes

Reject unknown properties

new ClassValidatorPipe({ validator: { forbidNonWhitelisted: true } })

Disable implicit conversion

new ClassValidatorPipe({ transform: { enableImplicitConversion: false } })

Nested DTOs

Use @ValidateNested() and @Type() from class-validator and class-transformer:

import { ValidateNested } from 'class-validator'
import { Type } from 'class-transformer'

class AddressDto {
	@IsString()
	street: string
}

class CreateUserDto {
	@ValidateNested()
	@Type(() => AddressDto)
	address: AddressDto
}

Troubleshooting

| Issue | Cause | Solution | | ------------------------------------ | ------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------- | | Validation failed (generic) | Internal error from class-validator/class-transformer | Check DTO decorators; ensure reflect-metadata is imported before HonestJS | | Body not validated | DTO not used as parameter type | Use @Body() body: CreateUserDto so metatype is available | | plainToInstance / decorator errors | Missing reflect-metadata or experimentalDecorators | Add import 'reflect-metadata' at app entry; enable experimentalDecorators and emitDecoratorMetadata in tsconfig | | Empty error message | All validation errors lack constraints | Rare; ensure DTOs use standard class-validator decorators |

License

MIT © Orkhan Karimov