How to customize price lookup

(needs review)

Price lookup logic

Trade transaction (sale/purchase) is represented by a Movement which defines the price charged. Price is obtained from the Movement by Movement.getPrice method. The way the price is calculated works as follows:

• if a price is set locally on the Movement, it is returned without any further ado

• then look for a type-based method [PortalType]_getPriceCalculationOperandDict, which if present should return a dict containig at least the 'price' key - this price is then used

• then the accessor uses a method "Movement_getPriceCalculationOperandDict" which:
  • if the Movement has no 'resource' defined returns its 'default' argument

  • if the Movement has 'explanation' related object (usu. and order or an invoice), looks for applicable TradeCondition objects

  • calls Resource.getPriceCalculationOperandDict

• the Resource.getPriceCalculationOperandDict looks for a type-based method [PortalType]_getPriceCalculationOperandDict (but this time on the Resource's portal type)

• then it looks for a type-based method [PortalType]_getPrice which can return just a price

• failing that, it applies a mindbogglingly complicated logic to calculate a price and a number of price-related parameters (e.g. discount) from Sale/Purchase Supply Lines, using also trade condition lines it may have received from the caller

Customisation

In nearly all cases, it is sufficient to use either the first or the last point, which means:

• set the price locally on Movement using Movement.setPrice method (programmatically or using a form field)
• create and configure Sale/Purchase Supplies to define a price of a resource, possibly differentiated by date, buyer, buyer's region, product variation or whatever you want - Supplies are a powerful tool

If you really need to apply your own logic, create a [PortalType]_getPriceCalculationOperandDict method, either for a Movement or for a Resource ([PortalType]_getPrice is deprecated)