[Backend] Build Production-Grade RSVP & Registration System (Solo/Team, Validation, Approval Workflow, Secure Data)

[abhishek-nexgen-dev]

We are building a complete RSVP & registration system for events like:

hackathons
meetups
workshops
competitions
conferences

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Core Flow

User opens RSVP page
→ fills form (solo/team)
→ submits registration
→ backend validates + saves
→ status = Pending / Waitlisted
→ admin reviews
→ Approved / Rejected
→ participant check-in

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🎯 Goals

System must be:

• Flexible (supports all event types)
• Secure (PII + Aadhaar handling)
• Scalable (10K+ registrations/event)
• Configurable (custom questions, rules)
• Production-ready (validation + workflows)

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🧱 CORE MODULES

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1️⃣ RSVP CONFIG SYSTEM

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Purpose

Each event has its own configuration.

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Endpoint

GET   /api/v1/events/:eventId/rsvp-config
PATCH /api/v1/events/:eventId/rsvp-config

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Features

enable/disable RSVP
start/end time window
allow solo/team
min/max team size
capacity limit
waitlist toggle
duplicate policy
custom questions

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2️⃣ REGISTRATION SYSTEM

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Endpoint

POST /api/v1/events/:eventId/rsvp

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Modes

Solo
Team

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Backend Flow

validate payload (Zod)
→ load RSVP config
→ enforce rules
→ check duplicates
→ validate team logic
→ encrypt sensitive data
→ generate registrationNumber
→ assign status (Pending/Waitlisted)
→ save
→ audit log

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3️⃣ VALIDATION SYSTEM (CRITICAL)

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Must Validate

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Basic

eventId required
leader fullName/email/mobile required
consents must be true

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Team Rules

teamName required
teamSize >= 2
members = teamSize - 1

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Solo Rules

teamSize = 1
members = []

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Identity

• email format
• mobile format (E.164)
• Aadhaar = 12 digits (if required)

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4️⃣ DUPLICATE & FRAUD PROTECTION

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Prevent

duplicate email in same event
duplicate mobile
duplicate collegeId (optional)
duplicate inside same payload

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Advanced

• block disposable emails
• OTP verification (optional)
• IP tracking

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5️⃣ RSVP WINDOW & CAPACITY

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Rules

reject before start
reject after end

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Capacity Handling

if full → Waitlisted
else → Pending

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6️⃣ STATUS WORKFLOW

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Lifecycle

Pending → Approved → CheckedIn
Pending → Rejected
Pending → Waitlisted → Approved
Approved → Cancelled

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Rules

• only Approved → check-in
• rejected cannot check-in

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7️⃣ ADMIN SYSTEM

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Endpoints

GET   /api/v1/events/:eventId/registrations
GET   /api/v1/events/:eventId/registrations/:id
PATCH /api/v1/events/:eventId/registrations/:id/approve
PATCH /api/v1/events/:eventId/registrations/:id/reject
PATCH /api/v1/events/:eventId/registrations/:id/waitlist
PATCH /api/v1/events/:eventId/registrations/:id/check-in
GET   /api/v1/events/:eventId/registrations/export

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Features

• search
• filter (status, type)
• pagination
• CSV export

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8️⃣ DATABASE DESIGN

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Collections

EventRSVPConfig
EventRegistration

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Indexes (IMPORTANT)

eventId
status
leader.email
leader.mobile
createdAt

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9️⃣ SENSITIVE DATA SECURITY 🔐

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Aadhaar Handling

encrypt before storing
store last4 only
never expose full value

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Compliance

• consent version stored
• data masking in responses
• audit logs for export

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🔟 CUSTOM QUESTIONS SYSTEM

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Supported Types

short text
long text
select
multi-select
number
file upload
url

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Validation

• required questions enforced
• type-safe answers

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1️⃣1️⃣ EVENT INTEGRATION

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System connects with:

Event system
Community system
Member system

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Example

• approved RSVP → create Member

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1️⃣2️⃣ AUDIT LOGGING

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Track

registration_created
status_changed
approved/rejected
export_downloaded
checkin_done

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1️⃣3️⃣ ANALYTICS

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Metrics

total registrations
approved count
rejected count
waitlist count
check-in rate

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1️⃣4️⃣ ERROR HANDLING

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Format

{
  "success": false,
  "message": "Team size invalid"
}

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1️⃣5️⃣ RATE LIMITING

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RSVP submit → 5/min/IP

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1️⃣6️⃣ TESTING

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Unit

• validation logic
• duplicate checks

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Integration

• full RSVP flow
• admin actions

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Security

• data masking
• rate limit

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1️⃣7️⃣ EDGE CASES

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duplicate registration
invalid team size
expired RSVP window
capacity overflow
invalid Aadhaar
CSV export misuse

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⚙️ PERFORMANCE

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• indexed queries
• pagination
• async processing

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🌍 ENVIRONMENT

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DEV
STAGING
PROD

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📦 ARCHITECTURE

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/controllers
/services
/models
/validators
/utils

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✅ ACCEPTANCE CRITERIA

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✔ RSVP submission works
✔ Solo + Team logic works
✔ Validation enforced
✔ Duplicate protection active
✔ Admin approval system works
✔ Check-in works
✔ Aadhaar securely handled
✔ Custom questions supported
✔ Export works
✔ Fully tested

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🔥 FINAL SUMMARY

This system behaves like:

Devfolio / HackerEarth / Eventbrite backend