Simple Banking System (Django REST Framework)

Group Members

150140-Owen Kipkosgei 121238-Ogole Edgar 151751-Mary Ng'ang'a 145768-Ogato Deborah Kerubo 94944-Antony Wanderi 169648-Kamau Joseph Manene 167242-Nyoike Brian Njehia

Project Overview

This project is a Simple Banking System implemented using Django and Django REST Framework (DRF).
It provides API endpoints to manage Accounts and Transactions with full CRUD functionality, validation, and automated testing.

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Step-by-Step Implementation

1. Models and Relationships

• Customer – first/last name, email (unique), phone (unique, validated), address.
  Relationship: One Customer → Many Accounts, Many Loans.

• Branch – name, code (unique), city.
  Relationship: One Branch → Many Accounts (PROTECT on delete).

• Account – account number (unique), type (Savings/Current), balance (non-negative), is_active.
  Relationship: One Customer → Many Accounts; One Branch → Many Accounts; One Account → One Card.

• Transaction – account (FK), txn_type (Deposit/Withdraw), amount (>0), reference (unique), performed_at.
  Relationship: One Account → Many Transactions.

• Loan – customer (FK), principal_amount (>0), interest_rate (≥0), status (Pending/Approved/Repaid), dates.
  Relationship: One Customer → Many Loans.

• Card – account (OneToOne), card_number (16 digits, unique), card_type (Debit/Credit), expiry_date, is_active.

All models inherit timestamps (created_at, updated_at) via an abstract

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2. Serializers and Validation

• CustomerSerializer, BranchSerializer, AccountSerializer, CardSerializer, LoanSerializer, TransactionSerializer
• Key validation rules:
  • Account.balance cannot be negative.
  • Card.card_number must be exactly 16 digits.
  • Loan.principal_amount > 0, Loan.interest_rate ≥ 0.
  • Transaction.amount > 0; withdrawals require sufficient balance; account must be active.
  • Transaction.create() updates the linked account balance atomically.

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3. Views / ViewSets

• ModelViewSet used for each model: CustomerViewSet, BranchViewSet, AccountViewSet, CardViewSet, LoanViewSet, TransactionViewSet.
• Permissions: IsAuthenticated (session login via /api-auth/login/ or admin login).

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4. URL Patterns

Base prefix: /api/

• /api/customers/
• /api/branches/
• /api/accounts/
• /api/cards/
• /api/loans/
• /api/transactions/

Other helpful routes:

• /admin/ – Django admin

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5. Testing Summary

We used Django’s built-in testing framework to validate functionality.

Test Cases Covered:

• ✅ Account creation and retrieval
• ✅ Updating and deleting accounts
• ✅ Creating valid deposits and withdrawals
• ✅ Preventing withdrawals larger than balance
• ✅ Ensuring account balance updates correctly after transactions

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Testing Evidence

The following is the actual output from running python manage.py test: