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The filter() method is used to filter you search, and allows you to return only the rows that matches the search term.
Yes, you can reuse existing querysets. This is not really making anything faster though, in fact, this code block won't even execute a query against the database because Django QuerySets are lazily evaluated. What I means is that it won't send the query to the database until you actually need the values.
To filter a Python Django query with a list of values, we can use the filter method with in . to search Blog entries with pk set to 1,4 or 7 by calling Blog. objects. filter with the pk_in argument set to [1, 4, 7] .
Such lookups are implemented in django.views.generic.date_based as follows:
{'date_time_field__range': (datetime.datetime.combine(date, datetime.time.min),
datetime.datetime.combine(date, datetime.time.max))}
Because it is quite verbose there are plans to improve the syntax using __date operator. Check "#9596 Comparing a DateTimeField to a date is too hard" for more details.
YourModel.objects.filter(datetime_published__year='2008',
datetime_published__month='03',
datetime_published__day='27')
// edit after comments
YourModel.objects.filter(datetime_published=datetime(2008, 03, 27))
doest not work because it creates a datetime object with time values set to 0, so the time in database doesn't match.
Here are the results I got with ipython's timeit function:
from datetime import date
today = date.today()
timeit[Model.objects.filter(date_created__year=today.year, date_created__month=today.month, date_created__day=today.day)]
1000 loops, best of 3: 652 us per loop
timeit[Model.objects.filter(date_created__gte=today)]
1000 loops, best of 3: 631 us per loop
timeit[Model.objects.filter(date_created__startswith=today)]
1000 loops, best of 3: 541 us per loop
timeit[Model.objects.filter(date_created__contains=today)]
1000 loops, best of 3: 536 us per loop
contains seems to be faster.
Now Django has __date queryset filter to query datetime objects against dates in development version. Thus, it will be available in 1.9 soon.
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