根據參數簡化QuerySet調用

Question

比方說，我有一個變量time_period，其值爲以下字符串之一：weekly，monthly,yearly。

...和一個QuerySet呼叫通過模型TimeModel過濾：

time_period = 'monthly' 
instance = TimeModel.objects.get(time_period=time_period, 
           year=datetime.now().year, 
           month=datetime.now().month) 

在這種情況下，我傳遞的參數year和month，因爲time_period == 'monthly'。如果time_period == yearly，我只想通過year，如果time_period == weekly，我會通過這三個（yearly，monthly和weekly）英寸

有什麼我已經寫3 if的描述短做的任何方式聲明？

Answer 1

也許這會有所幫助：

from django.db.models import Q 

now = datetime.now() 
time_periods = { 
    'weekly': Q(year=now.year, month=now.month, day=now.week), # note from OP: now.week is technically invalid; you actually want to use now.isocalendar()[1] 
    'monthly': Q(year=now.year, month=now.month), 
    'yearly': Q(year=now.year), 
} 

instance = TimeModel.objects.get(time_periods[time_period], time_period=time_period)