Sometimes one may wish to query the database for objects matching any of several criteria specified in several form fields, some of which may be multiple choice. This function makes that easy:

def buildOrQuery(request, config):
	'''
	Builds a django.db.models.query.QOr object based on HTTP request and a
	simple config dictionary, mapping field names to filter syntax.  For
	example:
    	config = {
    		'bar': 'foo__bar__exact',
    		'ham': 'spam__eggs__ham__icontains',
    	}
	'''
	query = None # A blank query here would be v bad
	for field in config.keys():
		values = request.POST.getlist(field)
		for value in values:
			subquery = Q(**{config[field]: value})
			if not query:
				query = subquery
			else:
				# Combine using OR:
				query = query | subquery
	if query:
		return query
	else:
		return Q() # Blank query -- it would break things to return None