money-lib

Python 3 money lib with decimal precision and currency exchange support.

Installation

Install the latest release with:

pip install money-lib

Usage

A Currency object can be created with a currency_code (must be a string and valid ISO 4217 format: ^[A-Z]{3}$).

>>> from money import Currency
>>> currency = Currency('USD')
>>> currency
Currency('USD')

A Money object can be created with an amount (can be any valid value in decimal.Decimal(value)) and a currency (can be a string or a Currency(code) object).

>>> from money import Money
>>> money = Money('7.37', 'USD')
>>> money
Money(Decimal('7.37'), 'USD')

Money objects are immutable by convention and hashable. Once created, you can use read-only properties amount (decimal.Decimal) and currency (Currency) to access its internal components. The amount property returns the amount rounded to the correct number of decimal places for the currency.

>>> money = Money('6.831', 'USD')
>>> money.amount
Decimal('6.83')
>>> money.currency
Currency('USD')

Money can apply most arithmetic and comparison operators between money objects, integers (int) and decimal numbers (decimal.Decimal).

>>> money = Money('5', 'USD')
>>> money / 2
Money(Decimal('2.5'), 'USD')
>>> money + Money('10', 'USD')
Money(Decimal('15'), 'USD')

All comparison and arithmetic operators support automatic currency conversion as long as you have a currency exchange backend setup. The currency of the leftmost object has priority.

# Assuming the rate from USD to EUR is 2
>>> money = Money('7.50', 'USD')
>>> money + Money('5', 'EUR')
Money(Decimal('10.00'), 'USD')

Money supports formatting for different locales.

>>> money = Money('13.65', 'USD')
>>> money.format()
'$13.65'
>>> money.format('pt_PT')
'13,65 US$'

Currency exchange

Currency exchange works by setting a backend class that implements the abstract base class money.exchange.BaseBackend. Its API is exposed through money.xrates, along with xrates.backend and xrates.backend_name.

A simple proof-of-concept backend money.exchange.SimpleBackend is included.

>>> from decimal import Decimal
>>> from money import Money, xrates

>>> xrates.backend = 'money.exchange.SimpleBackend'
>>> xrates.base = 'USD'
>>> xrates.setrate('AAA', Decimal('2'))
>>> xrates.setrate('BBB', Decimal('8'))

>>> a = Money('1', 'AAA')
>>> b = Money('1', 'BBB')

>>> assert a.to('BBB') == Money('4', 'BBB')
>>> assert b.to('AAA') == Money('0.25', 'AAA')
>>> assert a + b == Money('1.25', 'AAA')

Django integration

Model fields usage:

>>> from django.db import models
>>> from money import fields, Money

>>> class Product(models.Model):
...     price = fields.MoneyField(max_digits=19, decimal_places=4, default=Money('10', 'USD'))

Model queries usage:

# MoneyField creates another field (MoneyField name + '_currency') to store the currency
>>> Product.objects.create(price=Money('10', 'USD'))
>>> Product.objects.create(price='10', price_currency='USD')

# Get all products where price is greater than 4 and the currency equals 'USD'
>>> product = Product.objects.filter(price__gt=4, price_currency='USD').first()
>>> product.price
Money(Decimal('10.0000'), 'USD')

Credits

Currency exchange support based on https://github.com/carlospalol/money.

Django model multiple database columns by miracle2k.

Currency data and formatting is powered by Babel.