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CampusBite uses MongoDB with Mongoose ODM for data persistence. You can use MongoDB Atlas (cloud) or a self-hosted instance.

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Connection string

CampusBite reads the MongoDB connection string from environment variables:
backend/src/config/db.js
const uri = process.env.MONGODB_URI || process.env.DATABASE_URL
You can set either MONGODB_URI or DATABASE_URL. If both are set, MONGODB_URI takes precedence.

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MongoDB Atlas (cloud)

1

Create a free cluster

Sign up at mongodb.com/cloud/atlas and create a free M0 cluster.
2

Configure network access

Add your IP address to the IP Access List:
  • Go to Network Access → Add IP Address
  • For development: Click Allow Access from Anywhere (0.0.0.0/0)
  • For production: Add your server’s IP or use VPC peering
3

Create a database user

Go to Database Access and create a new user with read/write permissions to your database.
4

Get the connection string

Click Connect → Connect your application and copy the connection string:
mongodb+srv://username:[email protected]/campusbite?retryWrites=true&w=majority
Replace username and password with your database credentials.
5

Set the environment variable

export MONGODB_URI="mongodb+srv://username:[email protected]/campusbite"

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DNS resolution issues

If you encounter SRV DNS lookup errors (common in restrictive networks): 
querySrv ECONNREFUSED _mongodb._tcp.cluster.mongodb.net
Switch to a non-SRV connection string: 
mongodb+srv://username:[email protected]/campusbite
You can find the non-SRV connection string in Atlas under Connect → Connect your application → Connection String Only → Standard (non-SRV).

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Self-hosted MongoDB

For local development or self-hosted production:
1

Install MongoDB

Follow the official installation guide for your platform.
brew tap mongodb/brew
brew install mongodb-community
brew services start mongodb-community
2

Create a database and user

mongosh

use campusbite
db.createUser({
  user: "campusbite_user",
  pwd: "secure_password",
  roles: [{ role: "readWrite", db: "campusbite" }]
})
3

Set the connection string

# No authentication
export MONGODB_URI="mongodb://localhost:27017/campusbite"

# With authentication
export MONGODB_URI="mongodb://campusbite_user:secure_password@localhost:27017/campusbite"

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Database initialization

CampusBite automatically connects to MongoDB on startup:
backend/src/config/db.js
export const initDatabase = async () => {
  const uri = getMongoUri()
  const dbName = process.env.MONGODB_DB_NAME || undefined

  try {
    await mongoose.connect(uri, {
      dbName,
      serverSelectionTimeoutMS: 5000,
    })
  } catch (error) {
    // Error handling with helpful guidance
  }
}
Key behaviors:
  • Connection timeout: 5 seconds
  • Database name: Extracted from connection string or set via MONGODB_DB_NAME
  • Error guidance: Provides specific troubleshooting steps for SRV DNS failures

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Specifying database name

You can specify the database name in two ways: 
MONGODB_URI="mongodb://localhost:27017/campusbite"
#                                        ^^^^^^^^^^^
#                                        database name
If both are specified, MONGODB_DB_NAME takes precedence.

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Connection validation

The server performs preflight checks at startup:
backend/src/config/preflight.js
const REQUIRED_ENV_VARS = [
  "JWT_SECRET",
  "JWT_REFRESH_SECRET",
  "MONGODB_URI",
  "FRONTEND_URL",
];
If MONGODB_URI is missing or empty, the server will exit with: 
[Startup] Missing required environment variables: MONGODB_URI

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Troubleshooting

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Connection refused

MongoServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017
Solution: Ensure MongoDB is running: 
# macOS
brew services list | grep mongodb

# Linux
sudo systemctl status mongod

# Docker
docker ps | grep mongo

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Authentication failed

MongoServerError: Authentication failed
Solution: Verify credentials in your connection string: 
# Test connection with mongosh
mongosh "mongodb://username:password@host:27017/campusbite"

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SRV DNS lookup failed

querySrv ECONNREFUSED _mongodb._tcp.cluster.mongodb.net
Solution: The application provides automatic guidance: 
SRV DNS lookup failed. Your network/DNS is blocking Atlas SRV resolution.
Use Atlas non-SRV connection string (mongodb://...) or fix DNS access.
Switch to a non-SRV connection string (see DNS resolution issues).

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Database timeout

MongoServerSelectionError: Server selection timed out after 5000 ms
Solution:
  1. Check network connectivity to your MongoDB host
  2. Verify firewall rules allow outbound connections on port 27017
  3. For Atlas, ensure your IP is whitelisted in Network Access

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Collections

CampusBite uses the following MongoDB collections (created automatically via Mongoose schemas):
  • users - User accounts (students, vendors, admins)
  • stores - Vendor stores and menus
  • menuitems - Menu items for each store
  • orders - Order history and status
  • notifications - Real-time notifications
No manual schema setup is required. Mongoose creates collections on first document insert.

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