Error Classes

LightTs provides HttpError and specific error classes like ConflictError and BadRequestError to standardize error handling. Generated by lts add responses, these classes and a middleware handler ensure consistent error responses using native Node.js and Express.

Generated Files

The lts add responses command adds the following to src/core/errors/, using kebab-case for file names:

• Directorysrc/

  • Directorycore/

    • Directoryerrors/

      • bad-request.error.ts
      • conflict.error.ts
      • forbidden.error.ts
      • handler.error.ts
      • index.ts
      • not-found.error.ts
      • server-error.error.ts
      • unauthorized.error.ts

Error Classes

These classes use camelCase for methods and variables, supporting common HTTP errors.

HttpError

src/core/errors/index.ts

import { Request, Response } from 'express';

export class HttpError extends Error {
  public readonly statusCode: number;
  public readonly details?: any;

  constructor(statusCode: number, message: string, details?: any) {
    super(message);
    this.statusCode = statusCode;
    this.details = details;
    this.name = this.constructor.name;
    Error.captureStackTrace(this, this.constructor);
  }

  static middleware(err: any, req: Request, res: Response) {
    const statusCode = err.statusCode || 500;

    res.status(statusCode).json({
      success: false,
      message: err.message || 'internal server error'
    });
  }
}

ConflictError

src/core/errors/conflict.error.ts

import { HttpError } from '.';

export class ConflictError extends HttpError {
  constructor(message: string = 'conflict', details?: any) {
    super(409, message, details);
  }
}

BadRequestError

src/core/errors/bad-request.error.ts

import { HttpError } from '.';

export class BadRequestError extends HttpError {
  constructor(message: string = 'bad request', details?: any) {
    super(400, message, details);
  }
}

Setup Error Middleware

Add the error middleware to your application:

index.ts

import { HttpError } from '@/core/errors';
...

// Error middleware
app.use(HttpError.middleware);

...

Example Usage

Throw error classes in your services, paired with a simple controller (Express Router).

Service

src/modules/user/user.service.ts

import { BadRequestError } from '@/core/errors/bad-request.error';
import { ConflictError } from '@/core/errors/conflict.error';
import { DataResponse } from '@/core/responses/data.response';
import { MessageResponse } from '@/core/responses/message.response';
import { Request, Response } from 'express';

export default {
  getUsers: async (req: Request, res: Response) => {
    const users = [{ id: 1, name: 'John Doe' }];

    return new DataResponse(res, {
      data: users,
      message: 'Users fetched!',
      statusCode: 200,
    });
  },
  createUser: async (req: Request, res: Response) => {
    const { email } = req.body;
    if (!email) throw new BadRequestError('Email is required!');

    if (email === '[email protected]') throw new ConflictError('Email already exists!');

    return new MessageResponse(res, { message: 'User created!', statusCode: 201 });
  },
};

Notes

• Customization: Extend HttpError in src/core/errors/ for custom error types.
• Naming Conventions: Files use kebab-case (e.g., conflict.error.ts), classes and methods use camelCase (e.g., ConflictError, throwError).
• Error Handling: Place HttpError.middleware last in src/index.ts to catch all errors.
• Available Errors: Includes BadRequestError (400), ConflictError (409), ForbiddenError (403), NotFoundError (404), UnauthorizedError (401), and ServerError (500).

See Errors in Action Try a user management API with standardized error handling.