dj-wallet 0.1.0

A secure, flexible virtual wallet system for Django applications

dj-wallets

A secure, flexible, and powerful virtual wallet system for Django applications.

Inspired by laravel-wallet

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What is a Virtual Wallet?

Think of this as a "digital bank account" inside your app. It doesn't handle real money directly (like Stripe or PayPal), but it keeps track of a virtual balance for your users.

• Deposit: Adds "money" to the user's balance.
• Withdraw: Takes "money" away from the balance.
• Pay: Automatically deducts the cost of an item from the user's wallet and (optionally) transfers it to the seller.
• Safe: Behind the scenes, the library ensures that two transactions can't happen at the exact same time to break the balance (Race Condition Protection).

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Features

• Multi-Wallet Support: Each user can have multiple wallets (default, savings, USD, etc.).
• Atomic Transactions: Ensures data integrity during concurrent operations.
• Transfers & Exchanges: Move funds between users or between different wallets of the same user.
• Product Purchases: Built-in support for purchasing items using wallet balance.
• Polymorphic Holders: Attach wallets to any Django model (Users, Organizations, Teams).

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Installation

pip install dj-wallet

Add to your INSTALLED_APPS:

INSTALLED_APPS = [
    # ...
    'dj_wallet',
]

Run migrations:

python manage.py migrate

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Quick Start

1. Simple Setup

Add the WalletMixin to your custom User model to give it wallet capabilities.

from django.contrib.auth.models import AbstractUser
from dj_wallet.mixins import WalletMixin

class User(WalletMixin, AbstractUser):
    pass

2. Standard Operations

user = User.objects.create(username="khaled")

# Deposit: Adds to balance
user.deposit(500.00)

# Check balance
print(user.balance) # 500.00

# Withdraw: Deducts from balance
user.withdraw(100.00)

# Transfer: Deducts from one, adds to another
recipient = User.objects.create(username="friend")
user.transfer(recipient, 50.00)

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🛒 Buying Things (ProductMixin)

The library includes a robust system for handling product purchases. To make any Django model "buyable," apply the ProductMixin. This allows wallets to interact directly with your business logic.

1. Implementation

To make an item purchasable, implement the ProductMixin in your model:

from dj_wallet.mixins import ProductMixin
from django.db import models

class DigitalCourse(ProductMixin, models.Model):
    title = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)

    def get_amount_product(self, customer):
        """REQUIRED: Return the price for this specific customer."""
        return self.price

    def can_buy(self, customer, quantity=1):
        """OPTIONAL: Check inventory or eligibility (default: True)."""
        return True

    def get_meta_product(self):
        """OPTIONAL: Add transaction metadata (default: {})."""
        return {"course_id": self.id}

2. Available Methods (ProductMixin)

These methods should be defined in your product class:

• get_amount_product(customer): Returns the cost of the product. This is where you can implement dynamic pricing, discounts, or multi-currency logic.
• can_buy(customer, quantity): Validation logic before purchase. Return False to block the transaction (e.g., if out of stock).
• get_meta_product(): Provide extra data that will be saved in the transaction's meta JSON field for auditing.

3. Processing a Purchase

A holder can pay for a product using the .pay() method.

course = DigitalCourse.objects.get(id=1)

# This single line checks balance, validates availability, and transfers funds
try:
    transaction = user.pay(course)
    print("Course purchased successfully!")
except InsufficientFunds:
    print("Insufficient funds in wallet.")
except ProductNotAvailable:
    print("This item is currently out of stock.")

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Core Services

Django Wallets uses a component-based architecture where logic is encapsulated in services.

• WalletService: Base wallet operations (deposit, withdraw, reversals).
• TransferService: Fund movements between holders, refunds, and gifts.
• ExchangeService: Internal conversions between a holder's different wallets.
• PurchaseService: High-level logic for processing product payments.

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🛠️ Available Methods Reference

User/Holder Methods (via WalletMixin)

• .balance: Property that returns the current balance of the default wallet.
• .deposit(amount, meta=None, confirmed=True): Adds funds to the default wallet. Supports metadata and unconfirmed states.
• .withdraw(amount, meta=None, confirmed=True): Deducts funds. Raises InsufficientFunds if the balance is too low.
• .force_withdraw(amount): Deducts funds regardless of balance (allows negative balance).
• .transfer(to_holder, amount): Moves funds from this holder to another.
• .pay(product): High-level method to purchase an item implementing ProductMixin.
• .get_wallet(slug): Returns a specific wallet by name (creates it if it doesn't exist).
• .has_wallet(slug): Checks if a wallet exists without creating it.
• .freeze_wallet(slug): Locks a wallet from all incoming/outgoing transactions.
• .unfreeze_wallet(slug): Re-enables a frozen wallet.
• .get_pending_transactions(slug): Returns a QuerySet of transactions awaiting confirmation.

🏗️ Service Methods

For advanced usage, you can call services directly:

• WalletService.confirm_transaction(txn): Moves a transaction from PENDING to COMPLETED and updates the wallet balance.
• WalletService.reverse_transaction(txn): Perfectly undoes a transaction and records the reversal.
• TransferService.refund(transfer): Reverses a transfer and returns money to the sender.
• ExchangeService.exchange(holder, from_slug, to_slug, amount): Moves funds between two wallets owned by the same holder.

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Customization

1. Models

Extend the default models to add custom fields.

from dj_wallet.abstract_models import AbstractWallet

class MyWallet(AbstractWallet):
    tax_exempt = models.BooleanField(default=False)

2. Mixins

Override existing logic or add helpers by extending the WalletMixin.

from dj_wallet.mixins import WalletMixin

class MyCustomMixin(WalletMixin):
    def deposit(self, amount, meta=None, confirmed=True):
        print(f"User is depositing {amount}")
        return super().deposit(amount, meta, confirmed)

# settings.py
dj_wallet = {
    'WALLET_MIXIN_CLASS': 'myapp.mixins.MyCustomMixin',
}

3. Services

Override core business logic by extending the service classes.

from dj_wallet.services.common import WalletService

class MyWalletService(WalletService):
    @classmethod
    def deposit(cls, wallet, amount, **kwargs):
        # Your custom logic here
        return super().deposit(wallet, amount, **kwargs)

# settings.py
dj_wallet = {
    'WALLET_SERVICE_CLASS': 'myapp.services.MyWalletService',
}

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License

MIT License. See LICENSE for details.