Getting upcoming birthdays using 'date of birth' DateField

Question

I\'m trying to get the birthdays in the upcoming 20 days, given the below Person model:

class Person(models.Model):
    dob = models.DateField()  #          


        

Answer 1

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

Answer 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:

1. Normal month rollover. (e.g., June to July)
2. Leap days -- don't forget to check presence as well as absence of Feb 29.
3. 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:

• How to store birthdays without a year part?
• SQL Select Upcoming Birthdays
• mySQL SELECT upcoming birthdays

and so on. I just did a Google search for "stack overflow birthday select".

Answer 3

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