The purpose of this app is to allow adding dynamic conditions to relations between objects.
Let's say you develop an application that will present content to user based on various conditions. Gamification comes to mind. Let's say you want to set the conditions on a per-user or per-group basis. For example girls get happy hours on Saturday and boys get them on Thursdays. Hardcoding that would be a bit harsh if you tend to change your mind frequently.
Django >= 1.4
After installing the package and adding 'clausula' to INSTALLED_APPS you should define some abstract conditions you'd like to use.
Do this by creating a file conditions.py in your app. Then you need to import clauses registry, define your conditions and register them. Example conditions.py:
def day_of_week_clause(obj, *args, **kwargs):
import datetime
weekday = datetime.date.today().weekday()
if weekday == int(obj.param):
return True
return False
clauses.register(day_of_week_clause, "checks day of week")
Each condition is a function that fullows these rules:
- it takes one mandatory argument: an object (a :class:`Condition` instance)
- it silently accepts any number of optional arguments (*args, **kwargs)
- it returns a boolean value
clauses.register accepts two arguments: a callable and a string representation that will be displayed in Admin.
The object is guaranteed to have a param attribute which holds a string which can be used to compute returned boolean value. There can also be some relations available as :class:`Condition` is a subclass of :class:`django.db.models.Model`. Feel free to experiment and find some hackish uses for this package.