Unified API Response Architecture (ASP.NET Minimal API + Next.js)

This repository demonstrates a production-ready, fully typed Unified API Response System
for projects using ASP.NET Minimal API on the backend and Next.js on the frontend.

It solves common problems with API consistency, error handling, validation, and frontend–backend synchronization — while keeping the developer experience clean and strongly typed.

---

Features

Unified API response format across the whole backend

All endpoints return a consistent structure through ApiResponse<T>:

• success
• errorCode
• message
• data
• validationErrors (when needed)

No HTML errors, no raw exceptions — everything is structured JSON.

---

Strongly typed ErrorCode enum (C# → TypeScript autogeneration)

Forget about magic strings and typos like "UNAUHORIZED".

• Backend defines ErrorCode.cs (enum)
• Frontend imports generated errorCodes.ts
• Fully type-safe error handling
• No mismatch between backend and frontend — ever

---

Centralized error handling (middleware)

The backend includes:

• Global exception handler (500 → structured JSON)
• Authorization handler for:
  • 401 Unauthorized
  • 403 Forbidden
  • 404 Not Found
• Automatic validation response

Zero duplicated try/catch blocks.

---

Strongly Typed ApiError class (frontend)

Frontend wraps API errors via custom ApiError, allowing:

• consistent error handling
• IDE autocomplete for error.errorCode, error.validationErrors
• easy integration with React Hook Form, React Query, SWR, etc.

---

Validation errors with field-level details

Backend returns:

{
  "success": false,
  "errorCode": "ValidationError",
  "message": "Validation failed",
  "validationErrors": [
    { "field": "email", "message": "Email is required" },
    { "field": "password", "message": "Password must be at least 6 characters" }
  ]
}