UserModel

{ "_id": ObjectId, // Unique identifier for each user "name": "string", // Full name of the user "email": "string", // Email address "phone": "string", // Optional contact number "profilePicture": "string" // URL for the user's profile picture (optional) }

GruopModel { "_id": ObjectId, // Unique identifier for the group "name": "string", // Name of the group "createdBy": ObjectId, // Reference to the _id of the user who created the group "members": [ { "userId": ObjectId, // Reference to the user who is a member "balance": { "toPay": [ { "payeeId": ObjectId, // User who is to be paid "amount": "number" // Amount to pay } ], "toReceive": [ { "payerId": ObjectId, // User who owes money "amount": "number" // Amount to receive } ] } } ], "totalBalance": { "toPay": "number", // Total amount the group needs to pay "toReceive": "number" // Total amount the group is owed }, "expenses": [ObjectId], // References to associated expenses "createdAt": Date // Timestamp when the group was created }

ExpenseModel

{ "_id": ObjectId, // Unique identifier for each expense "groupId": ObjectId, // Reference to the _id of the group "createdBy": ObjectId, // Reference to the _id of the user who created the expense "title": "string", // Short description of the expense "totalAmount": "number", // Total amount of the expense "date": "Date", // Date when the expense occurred "createdAt": "Date", // Timestamp when the expense was added "splitDetails": [ { "payerId": ObjectId, // Reference to the _id of the user who paid "payeeId": ObjectId, // Reference to the _id of the user who owes money "amount": "number" // Amount owed by the payee to the payer } ] }