Unit System Explication

The most important feature in Polemian EC-CMS is the way how products can be ordered: trough amounts of a certain units not just one (most webshops only support ordering by piece). In order to implement this a unit system had to be implemented, products are given a certain unit, amount and minimum amount. This way shoppers can order a certain amount of a product like 500gr of potatoes or 2 gallons of water. But just as well 5 pieces or 1 ex. of another product like a book or wooden door.

The current unit system is build upon the idea of extensibility. Every unit is completely independent and has only three parameters: a name, a shorthand and a language. For example 'kilogram', 'kg.' and 'eng'. The language parameter is to separate units into language dependent groups because for example Kg and pound don't fit together.

A products unit values are amount and minimum amount. Amount states the quantity of the unit in which the product is sold and minimum amount tells us the minimum amount that can be bought. minimum amount is a calculation of the parameter of 'amount' multiplied by 'minimum amount'. This is very complicated so let's clarify.

			  Product 'Carrotes'.
			  
			  amount:		2
			  unit:			kg (metric system)
			  minimum amount:	3

This means a shopper can buy carrotes per 2 kilogram (Kg) but has to order at least 6 kilograms (3 x 2Kg). So he/she can order 6Kg, 8kg and so on, but not 5kg, 7Kg, etc...

Since every unit has to be entered independently, they are not aware of their kind: Given a certain unit there is no way to know wetter it is a unit of measure, weight or the like. Also is there no way to differentiate between different unit systems (most importantly, metric system and english/US.costomary system).

Also it would be better if the application already provided a list of units to get this task of the administrators back. The only problem there is the overhead: Unit selection lists would become bigger and less attractive.

For the next feature release, a new unit system will have to be designed that solves these problems. Listed below are the goals for such a system.