This is totally off the top of my head and may not compile or work :)
But something like this might be what you're looking for:
# Example Model
class MyModel(models.Model):
start_time = models.TimeField()
# Example query
from django.db.models import Q
from django.db.model import Max
# Get the maximum start time before the specified start time (3pm)
result =
MyModel.objects.filter(start_time__lt='15:00:00').aggregate(Max(start_time))
# Build two Q objects to represent the two cases we want
# 1.) The last meeting before the specified time (3pm) - we got the
last start time via the aggregation
latest_meeting = Q(start_time=result['start_time__max'])
# 2.) All meetings between 3pm and 5pm
after_3_and_before_5 = Q(start_time__gte='15:00:00',
start_time__lte='17:00:00')
# Filter the objects by ORing the two Q objects together giving us:
# "show me all objects that are the last meeting before 3 or start
betweeen 3pm and 5pm"
MyModel.objects.filter(latest_meeting | after_3_and_before_5)
Not sure if this is what you're looking for or if it's even right :)
Dan Harris
dih0...@gmail.com
On Jun 11, 4:28 pm, Cesar Devera <cesardev...@gmail.com> wrote:
> I'm not sure how to do directly in Django ORM, but if you use plain
> SQL queries, you could do try:
>
> select * from conference_room cr1
> where cr1.start_time >=
> (select max(start_time) from conference_room cr2 where cr2.start_time
> < :yout_filter_time)
> and cr1.start_time < :your_filter_time
>
> the "select max" gives you the row immediately before your time
> range.
>
> if you don't want to use a plain SQL approach, you will have to do two
> accesses to the DB. then, there are several way to do so, like:
>
> ConferenceRoom.objects.filter(start_time__gt=ConferenceRoom.objects.filter(
> start_time__lt=your_start_time).aggregate(Max('start_time'))
> [:1].get().start_time).filter(start_time__lt=your_end_time)
>
> sorry. I'm not sure if I typed correctly, but it's the same idea of
> the SQL statement I mentioned before:
> 1. find the maximum date before your the start date of your time frame
> 2. find all events after that date (1) including it (greater and equal
> to) and before your end date
>
> hope it helps,
>
> regards,
>
> ---------
> On 10 jun, 10:56, illuminated <petrovic.mi...@gmail.com> wrote:
>
>
>
> > Hi all,
>
> > I'm writing a django app and need help with filtering results from DB.
>
> > There is a conference room and it's usage is stored in django model.
> > There is a field "start_time" (model.TimeField); no "end_time". When I
> > query the table with a time range (i.e. 3pm - 5pm) I would like to get
> > not only events that start within given time range, but also the one
> > currently running (the last one that started before 3pm).
>
> > The only solution I have in my mind at the moment is to have two
> > queries: one would return events starting within the range, other
> > would retrieve events before that, would sort them descending by time
> > and I'd get just the first row. Then I'd try to join these two
> > results.
>
> > Although the above algorithm would/should work, I was wondering if
> > there was more elegant way to this?
>
> > Thanks!
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