def on_date(self, *args):
first_week = Date.first_date_of_year(self.date.year, self.date.isoweekday()).isocalendar()[1]
last_week = Date.last_date_of_year(self.date.year, self.date.isoweekday()).isocalendar()[1]
min_week = first_week if first_week <= 2 else 0 # 0 is for last week of preceding year
max_week = Date.last_date_of_year(self.date.year, 4).isocalendar()[1] + 1 if last_week == 1 else last_week
isoyear, isoweek, _ = self.date.isocalendar()
if isoyear < self.date.year:
isoweek = 0
elif isoyear > self.date.year:
isoweek = max_week
self.cycle = max_week - min_week + 1
self.offset = min_week
self.selected_value = isoweek - self.offset
def on_year(self, *args):
self.max_year_week = Date.last_date_of_year(self.year, 4).isocalendar()[1]
self.max_prev_year_week = Date.last_date_of_year(self.year - 1, 4).isocalendar()[1]
def on_selected_value(self, *args):
if self.date is not None:
week = self.selected_value - (0 if self.zero_indexed else 1)
self.date = (Date.first_date_of_year(self.date.year, self.date.isoweekday()) +
datetime.timedelta(days=7 * week))