Eliminating the parent property name from the validation message of a nested object

Question

Eliminating the parent property name from the validation message of a nested object

When using @ValidateNested() with the class-validator library, I encountered a formatting issue when validating a nested object:

// Object Schema:
export class CreateServerSettingsDTO {
  @IsNotEmpty({ message: 'Username is required' })
  username: string;

  @IsNotEmpty({ message: 'Password is required' })
  password: string;
}

export class CreateServerDTO {
  @IsNotEmpty({ message: 'Server name is required' })
  serverName: string;

  description?: string;

  @ValidateNested()
  @Type(() => CreateServerSettingsDTO)
  @IsObject({ message: 'Settings must be an object' })
  @IsNotEmpty({ message: 'Settings are required' })
  settings: CreateServerSettingsDTO;
}

// Validation response:
{
  "statusCode": 400,
  "message": [
    "settings.Username is required",
    "settings.Password is required"
  ],
  "error": "Bad Request"
}

I am looking to customize the validation messages for the nested object under settings. Specifically, I want the messages to display as:

{
  "statusCode": 400,
  "message": [
    "Username is required",
    "Password is required"
  ],
  "error": "Bad Request"
}

I have tried different approaches but could not find a way to remove the settings. prefix from the nested property messages. Any suggestions on how this can be accomplished?

typescript nestjs class-validator

Answer 1

Answer №1

The most effective technique I discovered

formatErrors.ts

import { ValidationPipe, BadRequestException } from '@nestjs/common';
import { ValidationError } from 'class-validator';

type IErrorMessage = Record<string, any>;

function formatErrorsHelper(errors: ValidationError[]): IErrorMessage[] {
  return errors.map((item): IErrorMessage => {
    const { property, constraints, children } = item;
    const result: IErrorMessage = {};

    if (constraints) {
      result[property] = Object.values(constraints);
    }

    if (Array.isArray(children) && children.length > 0) {
      result[property] = formatErrorsHelper(children);
    }

    return result;
  });
}

export const formatErrorPipe = new ValidationPipe({
  exceptionFactory: (errors: ValidationError[]) => {
    return new BadRequestException(formatErrorsHelper(errors));
  },
});

main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app/app.module';
import { formatErrorPipe } from './helpers/formatErrors';

async function initialize() {
  const app = await NestFactory.create(AppModule);

  app.useGlobalPipes(formatErrorPipe);

  await app.listen(3000);
}
initialize();

Answer 2

The most effective technique I discovered

formatErrors.ts

import { ValidationPipe, BadRequestException } from '@nestjs/common';
import { ValidationError } from 'class-validator';

type IErrorMessage = Record<string, any>;

function formatErrorsHelper(errors: ValidationError[]): IErrorMessage[] {
  return errors.map((item): IErrorMessage => {
    const { property, constraints, children } = item;
    const result: IErrorMessage = {};

    if (constraints) {
      result[property] = Object.values(constraints);
    }

    if (Array.isArray(children) && children.length > 0) {
      result[property] = formatErrorsHelper(children);
    }

    return result;
  });
}

export const formatErrorPipe = new ValidationPipe({
  exceptionFactory: (errors: ValidationError[]) => {
    return new BadRequestException(formatErrorsHelper(errors));
  },
});

main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app/app.module';
import { formatErrorPipe } from './helpers/formatErrors';

async function initialize() {
  const app = await NestFactory.create(AppModule);

  app.useGlobalPipes(formatErrorPipe);

  await app.listen(3000);
}
initialize();

Answer 3

Answer №2

**handle-errors.ts**

import { ValidationPipe, BadRequestException } from '@nestjs/common';
import { ValidationError } from 'class-validator';

function handleErrors(errors: ValidationError[]): string[] {
  const errorMessages: string[] = [];

  function extractErrorMessage(error: ValidationError) {
    if (error.constraints) {
      errorMessages.push(...Object.values(error.constraints));
    }

    if (error.children && error.children.length > 0) {
      error.children.forEach(extractErrorMessage);
    }
  }

  errors.forEach(extractErrorMessage);

  return errorMessages;
}

export const formatErrorHandle = new ValidationPipe({
  whitelist: true,
  forbidNonWhitelisted: true,
  exceptionFactory: (errors: ValidationError[]) => {
    throw new BadRequestException(handleErrors(errors));
  },
});

main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app/app.module';
import { formatErrorHandle } from './helpers/errorHandler';

async function startApp() {
  const app = await NestFactory.create(AppModule);

  app.useGlobalPipes(formatErrorHandle);

  await app.listen(3000);
}
startApp();

Answer 4

**handle-errors.ts**

import { ValidationPipe, BadRequestException } from '@nestjs/common';
import { ValidationError } from 'class-validator';

function handleErrors(errors: ValidationError[]): string[] {
  const errorMessages: string[] = [];

  function extractErrorMessage(error: ValidationError) {
    if (error.constraints) {
      errorMessages.push(...Object.values(error.constraints));
    }

    if (error.children && error.children.length > 0) {
      error.children.forEach(extractErrorMessage);
    }
  }

  errors.forEach(extractErrorMessage);

  return errorMessages;
}

export const formatErrorHandle = new ValidationPipe({
  whitelist: true,
  forbidNonWhitelisted: true,
  exceptionFactory: (errors: ValidationError[]) => {
    throw new BadRequestException(handleErrors(errors));
  },
});

main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app/app.module';
import { formatErrorHandle } from './helpers/errorHandler';

async function startApp() {
  const app = await NestFactory.create(AppModule);

  app.useGlobalPipes(formatErrorHandle);

  await app.listen(3000);
}
startApp();

Eliminating the parent property name from the validation message of a nested object

Answer №1

Answer №2

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