Product model base implementation – you do not need to use this

It may save you some typing though.

class plata.product.models.ProductBase(*args, **kwargs)[source]

Product models must have two methods to be usable with Plata:

  • get_price: Return a price instance
  • handle_order_item: Fill in fields on the order item from the product, i.e. the name and the stock keeping unit.
get_price(currency=None, orderitem=None)[source]

This method is part of the public, required API of products. It returns either a price instance or raises a DoesNotExist exception.

If you need more complex pricing schemes, override this method with your own implementation.


This method has to ensure that the information on the order item is sufficient for posteriority. Old orders should always be complete even if the products have been changed or deleted in the meantime.

Product extensions

Exact, transactional stock tracking for Plata

Follow these steps to enable this module:

  • Ensure your product model has an items_in_stock field with the following definiton:

    items_in_stock = models.IntegerField(default=0)
  • Add 'plata.product.stock' to INSTALLED_APPS.

  • Set PLATA_STOCK_TRACKING = True to enable stock tracking in the checkout and payment processes.

  • Optionally modify your add-to-cart forms on product detail pages to take into account items_in_stock.

class plata.product.stock.models.Period(*args, **kwargs)[source]

A period in which stock changes are tracked

You might want to create a new period every year and create initial amount transactions for every variation.

StockTransaction.objects.open_new_period does this automatically.

class plata.product.stock.models.StockTransaction(*args, **kwargs)[source]

Stores stock transactions transactionally :-)

Stock transactions basically consist of a product variation reference, an amount, a type and a timestamp. The following types are available:

  • StockTransaction.INITIAL: Initial amount, used when filling in the stock database
  • StockTransaction.CORRECTION: Use this for any errors
  • StockTransaction.PURCHASE: Product purchase from a supplier
  • StockTransaction.SALE: Sales, f.e. through the webshop
  • StockTransaction.RETURNS: Returned products (i.e. from lending)
  • StockTransaction.RESERVATION: Reservations
  • StockTransaction.INCOMING: Generic warehousing
  • StockTransaction.OUTGOING: Generic warehousing
  • StockTransaction.PAYMENT_PROCESS_RESERVATION: Product reservation during payment process

Most of these types do not have a significance to Plata. The exceptions are:

  • INITIAL transactions are created by open_new_period
  • SALE transactions are created when orders are confirmed
  • PAYMENT_PROCESS_RESERVATION transactions are created by payment modules which send the user to a different domain for payment data entry (f.e. PayPal). These transactions are also special in that they are only valid for 15 minutes. After 15 minutes, other customers are able to put the product in their cart and proceed to checkout again. This time period is a security measure against customers buying products at the same time which cannot be delivered afterwards because stock isn’t available.

Check whether enough stock is available for all selected products, taking into account payment process reservations.