可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试):
问题:
I'm trying to get the birthdays in the upcoming 20 days, given the below Person model:
class Person(models.Model): dob = models.DateField() # date of birth
There are similar questions on SO already (here and here), but these do not cover my use case, as I'm storing a date of birth instead of the next birthday or a timefield.
I've tried to do some things like the following:
from datetime import timedelta, date today = date.today() next_20_days = today+timedelta(days=20) Person.objects.filter(dob__month=today.month, dob__day__range=[today.day, next_20_days.day])
... but I get FieldError: Unsupported lookup 'day' for DateField or join on the field not permitted.
When I do e.g. Person.objects.filter(dob__month=today.month, dob__day=next_20_days.day), I do get the results for exactly 20 days from now. So I potentially could go over each of the 20 days in a loop, but that seems rather ineffective.
Any idea on how to do this the proper way?
回答1:
FYI, I ended up doing the following which works for me and which does not require raw SQL. Any improvements would be welcomed :-)
# Get the upcoming birthdays in a list (which is ordered) for the amount of days specified def get_upcoming_birthdays(person_list, days): person_list= person_list.distinct() # ensure persons are only in the list once today = date.today() doblist = [] doblist.extend(list(person_list.filter(dob__month=today.month, dob__day=today.day))) next_day = today + timedelta(days=1) for day in range(0, days): doblist.extend(list(person_list.filter(dob__month=next_day.month, dob__day=next_day.day, dod__isnull=True))) next_day = next_day + timedelta(days=1) return doblist
回答2:
Caveat: I believe calendars and time is hard. As a result, I feel obligated to warn you that I haven't rigorously tested my proposal. But of course, I think it should work. :)
Unfortunately, I think you should abandon date objects as the additional complication of year data precludes easy selects. Rather, I propose storing the birthday as a MMDD string (comparison of strings works, as long as you format them consistently). You can then compute your next_20_days and convert that to a similar MMDD string, as well as today, then use them as values to compare against.
I have three edge cases you should definitely make sure work:
- Normal month rollover. (e.g., June to July)
- Leap days -- don't forget to check presence as well as absence of Feb 29.
- Year boundary -- you'll need to either do two queries and union the results, or do an
OR query using Q objects.
Edit: See also:
and so on. I just did a Google search for "stack overflow birthday select".
回答3:
I have been struggling with the same issue for the past days. I think I assembled a pretty solid solution that should allow you easily to derive all the birthdays to come up for the next X days. This query runs against the database-table geburtstage (birthdays) with the following 4 fields: ID (set as primary key) vorname (firstname), nachname (lastname) and geburtstag (birthday). Just create the table, fill in some records and run the query below:
select * FROM ( select curdate() AS today, DAY(CURDATE()) AS d_T, MONTH(CURDATE()) AS m_T, DAY(geburtstag) AS d_G, MONTH(geburtstag) AS m_G, subdate(CURDATE(),-20) AS date_20, DAY(subdate(CURDATE(),-20)) AS d_20, MONTH(subdate(CURDATE(),-20)) AS m_20, vorname, nachname, geburtstag, (YEAR(CURRENT_TIMESTAMP) - YEAR(geburtstag) +1 - CASE WHEN MONTH(CURRENT_TIMESTAMP) < MONTH(geburtstag) THEN 1 WHEN MONTH(CURRENT_TIMESTAMP) > MONTH(geburtstag) THEN 0 WHEN DAY(CURRENT_TIMESTAMP) <= DAY(geburtstag) THEN 1 ELSE 0 END) AS age, datediff(DATE_FORMAT(geburtstag,concat('%',YEAR(CURDATE()),'-%m-%d')),NOW()) AS no_of_days FROM geburtstage union select curdate() AS today, DAY(CURDATE()) AS d_T, MONTH(CURDATE()) AS m_T, DAY(geburtstag) AS d_G, MONTH(geburtstag) AS m_G, subdate(CURDATE(),-20) AS date_20, DAY(subdate(CURDATE(),-20)) AS d_20, MONTH(subdate(CURDATE(),-20)) AS m_20, vorname, nachname, geburtstag, (YEAR(CURRENT_TIMESTAMP) - YEAR(geburtstag) +1 - CASE WHEN MONTH(CURRENT_TIMESTAMP) < MONTH(geburtstag) THEN 1 WHEN MONTH(CURRENT_TIMESTAMP) > MONTH(geburtstag) THEN 0 WHEN DAY(CURRENT_TIMESTAMP) <= DAY(geburtstag) THEN 1 ELSE 0 END) AS age, datediff(DATE_FORMAT(geburtstag,concat('%',(YEAR(CURDATE())+1),'-%m-%d')),NOW()) AS no_of_days FROM geburtstage) AS upcomingbirthday WHERE no_of_days >=0 AND no_of_days <= 20 GROUP BY ID ORDER BY (m_G, d_G) < (m_T, d_T), m_G, d_G, geburtstag desc, age
