jpd-express-error

jpd-express-error is a lightweight utility package designed to standardize error handling in Express microservices.
It ensures consistent error responses, typed messages, and structured error propagation across your services.

Features

• Typed Messages → Success and error messages are strongly typed for better maintainability.
• Standardized API Responses → Ensures uniform response structures across all services.
• Custom Error Handling → Provides a centralized AppError class for better error propagation.
• Express & Microservices-Friendly → Built to simplify error management in Express applications.

Installation

npm install jpd-express-error

Usage

Handling success responses or throw an error

Use ApiResponse.success() to return a standardized success response. Use handleError(); to return a standardized error response.

/*
  Controller
*/

import { Request, Response } from 'express';
import { handleError, ApiResponse, AppError } from 'jpd-express-error';
import { createUserService } from '@/services/userService';

import { Request, Response } from 'express';
import { handleError, ApiResponse, AppError } from 'jpd-express-error';
import { createUserService } from '@/services/userService';

export const createUser = async (req: Request, res: Response): Promise<void> => {
  try {
    const { name, email, password } = req.body;

    if (!name || !email || !password) {
      throw new AppError('Missing required fields', 400);
    }

    const userData = { name, email, password };
    const user = await createUserService(userData);

    // Send a standardized success response
    res.status(201).json(ApiResponse.success('User created successfully', user));
  } catch (error: any) {
    handleError(error, res);
  }
};

Throwing Errors from Database Models

When an error occurs in the database, use AppError to propagate it to the service or controller.
The controller will catch the error and format it correctly using handleError().

Example: Throwing an error in a database model

import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library';
import { AppError } from 'jpd-express-error';

export const store = async (data: Omit<User, "id">): Promise<User> => {
  try {
    // 1️⃣ Create the resource in the database
    const response = await prisma.user.create(data);
    return response;
  } catch (error) {
    if (error instanceof PrismaClientKnownRequestError) {
      if (error.code === 'P2002') {
        throw new AppError('Resource already exists');
      }
    }
    throw error;
  }
};

Available Messages

✅ Success Messages • Resource retrieved successfully • Resource updated successfully • Resource validated successfully • Resource completed successfully • Operation succeeded • User logged in successfully • User logged out successfully • User registered successfully • Profile updated successfully • Resource created successfully • Resource deleted successfully

❌ Error Messages • Error logging out • Invalid request • Missing required fields • Invalid data format • Invalid request format • Unsupported media type • Too many parameters • Invalid query parameters • Cart creation failed • Unauthorized • Invalid password • Invalid token • Token expired • Missing token • Invalid credentials • Forbidden • Insufficient permissions • Access denied • Resource not found • User not found • Cart not found • Product not found • User already exists • Email already in use • Resource already exists • Foreign key constraint failed • Validation error • Invalid email format • Password too weak • Too many requests • Rate limit exceeded • Internal server error • Database connection error • File upload error • File deletion error • File read error • File write error • An error occurred while processing your request

Prisma-Specific Errors

When working with Prisma, you might encounter specific error codes. These errors can be caught and handled using AppError for proper error propagation.

•	P2002 → Unique constraint failed (e.g., trying to insert a duplicate email).
•	P2003 → Foreign key constraint failed (e.g., trying to delete a referenced record).
•	P2025 → Record not found (e.g., trying to update or delete a record that does not exist).
•	P2014 → Nested delete or disconnect is not allowed if parent record is required.
•	P2016 → Query interpretation error (e.g., invalid field or relation used in query).
•	P2017 → Related record not found (e.g., relation inconsistency).
•	P2018 → Required connected records not found.
•	P2022 → Database constraint violation (e.g., check constraint failed).
•	P2023 → Invalid database input (e.g., sending incorrect values).
•	P2024 → Database connection timeout or issues with the database server.

Contributing

Feel free to open issues or contribute by submitting pull requests! 🚀

License

This project is licensed under the ISC License.