ABOUT

django_price is an attempt to implement price representation for django, done the right way. Prices itself are very easy to implement, but may be done very wrong if it comes to do calculations including tax (or multiple taxes).

django_price features a Price class to represent net/tax/gross prices. This class may be added, multiplied, etc. like you would some "simple decimal" expect to behave. Internaly however it keeps track of all applied taxes and its corresponding net/tax/gross amounts. So adding two prices to calculate the total of - for example - an invoice does not loose important information (like which tax amounts are included).

WHY

As said above price calculation can go terribly wrong. This even happens for big players like Magento (10€ product + 5€ shipping = 15.01€ for 19% tax, before Magento 1.8). django_price tries to do things right to avoid such issues.

FEATURES

• Basic calculation for prices (including tax information)
• Knows the used currency (for rounding and formatting)
• Stores taxes to your database (LinearTax and Multitax)
• Proper rounding for prices (on demand, based on used currency)
• Utilities to:
  • Store prices to the database
  • Round prices based on the used currency

ROUNDING

django_price does implicit rounding when calculating the net/gross/tax amount of prices. In addition the raw/precise values are stored internally. So when you calculate with prices the calculations are always done using the precise prices, afterwards the rounded results are recalculated.

If you need prices to stay stable (10 times 100 should be exactly 1000) you may need to do explicit rounding. This should always happen when you need to display the amounts to anyone.

REQUIREMENTS

• Django (obviously)
• django_deferred_polymorph (may be skipped if you don't use the supplied models)