[C4GT Community] API Status Code Correction, Swagger Alignment & UI Error Handling in MMU-API & MMU-UI

[drtechie]

📄 Description

Fix improper use of HTTP 200 for error scenarios across AMRIT APIs (this ticket is created for MMU-API and MMU-UI), align all endpoints with REST standards, update Swagger/OpenAPI specifications, and ensure the UI correctly handles new status codes.

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🚨 Problem Statement

Currently, many AMRIT APIs always return 200 OK, even in cases of:

• Authentication failures
• Authorization failures
• Validation errors
• Business logic failures
• Server-side exceptions

Proper HTTP status codes like 401, 403, 400, 404, 409, and 500 are not consistently used.

This results in:

• Broken REST semantics
• UI relying on internal error flags instead of HTTP semantics
• Inaccurate Swagger / OpenAPI documentation
• Poor debuggability and error tracing
• Increased risk of silent failures in production

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🎯 Goal / Expected Outcome

• ✅ All APIs return correct HTTP status codes
• ✅ A standard error response structure is implemented
• ✅ Swagger/OpenAPI documentation reflects real response behavior
• ✅ Frontend/UI handles errors using 4xx and 5xx status codes
• ✅ Final system delivers:
  • REST-compliant APIs
  • Accurate Swagger documentation
  • Reliable UI error handling and messaging

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🔍 Current Issues Observed

• APIs return 200 even when:
  • Session is expired
  • User lacks permission
  • Input validation fails
  • Backend throws exceptions
• Error information is only embedded inside response bodies
• Swagger shows incorrect response codes
• UI cannot distinguish between:
  • Auth failures
  • Validation errors
  • Server crashes

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🛠️ Scope of Work

1️⃣ Backend Changes

• Identify APIs that incorrectly return 200 for error cases
• Implement correct status codes:
  • 400 → Validation errors
  • 401 → Unauthorized
  • 403 → Forbidden
  • 404 → Not found
  • 409 → Conflict
  • 500 → Internal Server Error
• Implement centralized exception handling using @ControllerAdvice
• Enforce a standard error response format,

✅ Acceptance Criteria

• APIs no longer return 200 for failure cases
• Correct HTTP status codes implemented and verified
• Centralized exception handling in place
• Swagger/OpenAPI accurately reflects real behavior
• UI handles 4xx and 5xx responses properly
• No regression in existing production workflows

[tanmaykule]

Hi @drtechie, I am here from the winter of code event. Can I be assigned this task?
If I have understood the task correctly, then I have to make sure the response code is appropriate for the type of error being thrown in the API call and make sure the frontend reflects that as well.