Re: django implementation group by every two hours,

['Tom Evans' via Django users]

On Tue, Jul 11, 2017 at 10:22 AM, kanhaiya yadav
 wrote:
> Hi,
>
> I have a model
> class XyzModel (models.Model):
>name = models.CharField(max_length=NAME_LENGTH)
>unique_id = models.CharField(max_length=NAME_LENGTH)
>info = models.CharField(max_length=NAME_LENGTH, blank=True)
>violation_time = models.DateTimeField()
>
>
>
>
> I have many rows in the database. So I want to group by the results for
> every two hours or for every four hours.
> I want the result something like
>
> name   violation_date
> interval counts
> abc   2017-07-01
> 06:00 - 08:00   20
> xyz   2017-07-01
> 08:00 - 10:00   30
>
> My query is
> XyzModel.objects
> .extra({"day": "date_trunc('hour',violation_time)"}
> .values("day")
> .order_by("day")
> .annotate(count=Count("id"))
> But using this query I can only group the result by one hour interval. I
> want to group by more than one hour interval.

You realise your "day" parameter is actually hours, right?

.extra({'day', 'TRUNC(EXTRACT(hour FROM violation_time) / 2)'})

'day' will then be the 0-based index of the 2 hour periods, starting
from midnight, so a value of 5 would mean 10 AM - 12 AM.

Cheers

Tom

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django implementation group by every two hours,

[kanhaiya yadav]

Hi,

I have a model 
class XyzModel (models.Model):
   name = models.CharField(max_length=NAME_LENGTH)
   unique_id = models.CharField(max_length=NAME_LENGTH)
   info = models.CharField(max_length=NAME_LENGTH, blank=True)
   violation_time = models.DateTimeField()




I have many rows in the database. So I want to group by the results for 
every two hours or for every four hours.
I want the result something like

name   violation_date   
interval counts
abc   2017-07-01 
 06:00 - 08:00   20
xyz   2017-07-01   
08:00 - 10:00   30

My query is 
XyzModel.objects
.extra({"day": "date_trunc('hour',violation_time)"}
.values("day")
.order_by("day")
.annotate(count=Count("id"))
But using this query I can only group the result by one hour interval. I 
want to group by more than one hour interval.

Thanks

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