I have a Django model with a created timestamp and I'd like to get the counts of objects created on each day. I was hoping to use the aggregation functionality in Django but I can't figure out how to solve my problem with it. Assuming that doesn't work I can always fall back to just getting all of the dates with values_list but I'd prefer to give the work to Django or the DB. How would you do it?
Alex pointed to the right answer in the comment:
Count number of records by date in Django
Credit goes to ara818
Guidoism.objects.extra({'created':"date(created)"}).values('created').annotate(created_count=Count('id'))
from django.db.models import Count
Guidoism.objects \
# get specific dates (not hours for example) and store in "created"
.extra({'created':"date(created)"})
# get a values list of only "created" defined earlier
.values('created')
# annotate each day by Count of Guidoism objects
.annotate(created_count=Count('id'))
I learn new tricks every day reading stack.. awesome!
Use the count method:
YourModel.objects.filter(published_on=datetime.date(2011, 4, 1)).count()
Related
I wanted to order a query set on the basis of a time of a datetime field.
I have used the following (here Tasks is my model and datetime is the field)
Tasks.objects.all().order_by('datetime.time')
this doesn't work and also
Tasks.objects.all().order_by('datetime__time')
doesn't work as it is part of the same model.
I tried using .annotate() but I don't know how exactly to do it.
How should I go about doing this?
Tasks.objects.all().order_by('datetime__hour')
or
Tasks.objects.all().order_by('datetime__minute')
Task.objects.all().order_by('datetime__hour', 'datetime__minute')
i come with this doubt abobt how to make a linked dates list based on existing objects, first of all i have a model with a DateTimeField which stores the date and hour that the object was added.
I have something like:
|pk|name|date
|1|name 1|2016-08-02 16:14:30.405305
|2|name 2|2016-08-02 16:15:30.405305
|3|name 3|2016-08-03 16:46:29.532976
|4|name 4|2016-08-04 16:46:29.532976
And i have some records with the same day but different hour, what i want is to make a list displaying only the unique days:
2016-08-02
2016-08-03
2016-08-04
And also because i'm using the CBV DayArchiveView i want to add a link to that elements to list them per day with a url pattern like this:
url(r'^archive/(?P<year>[0-9]{4})/(?P<month>[-\w]+)/(?P<day>[0-9]+)/$', ArticleDayArchiveView.as_view(), name="archive_day"),
The truth is that i don't have a clue of how to achieve that, can you help me with that?
Extracting unique dates
instances = YourModel.objects.all()
unique_dates = list(set(map(lambda x: x.date.strftime("%Y-%m-%d"), instances)))
About listing them, your url pattern looks ok. You need to define a view in order to retrieve them and wire up with that url.
UPDATE:
If you want to order them, just:
sorted_dates = sorted(unique_dates)
I've got a working SQL query that I'm trying to write in Django (without resorting to RAW) and was hoping you might be able to help.
Broadly, I'm looking to next two queries - the first calculates a COUNT, and then I'm looking to calculate an AVERAGE of the COUNTS. (this'll give you the average number of items on a ticket, per location)
The SQL that works is:
SELECT location_name, Avg(subq.num_tickets) FROM (
SELECT Count(ticketitem.id) AS num_tickets, location.name AS location_name
FROM ticketitem
JOIN ticket ON ticket.id = ticketitem.ticket_id
JOIN location ON location.id = ticket.location_id
JOIN location ON location.id = location.app_location_id
GROUP BY ticket_id, location.name) AS subq
GROUP BY subq.location_name;
For my Django code, I'm trying something like this:
# Get the first count
qs = TicketItem.objects.filter(<my complicated filter>).\
values('ticket__location__app_location__name','posticket').\
annotate(num_tickets=Count('id'))
# now get the average of the count
qs2 = qs.values('ticket__location__app_location__name').\
annotate(Avg('num_tickets')).\
order_by('location__app_location__name')
but that fails because num_tickets doesn't exist ... Anyway - suspect I'm being slow. Would love someone to enlighten me!
Check out the section on aggregating annotations from the Django docs. Their example takes an average of a count.
I was playing around with this a bit in a manage.py shell, and I think the django ORM might not be able to do that kind of annotation. Honestly you're probably going to have to resort to doing a raw query or bind in something like https://github.com/Deepwalker/aldjemy which would let you do that via SQLAlchemy.
When I playing with this I tried
(my_model.objects.filter(...)
.values('parent_id', 'parent__name', 'thing')
.annotate(Count('thing'))
.values('name', 'thing__count')
.annotate(Avg('thing__count')))
Which gave a lovely traceback about FieldError: Cannot compute Avg('thing__count'): 'thing__count' is an aggregate, which makes sense since I doubt the ORM is trying to convert that first group by to a nested query.
As far as I know, django does have lookups only for year, month and day. I am looking for something is equivalent to this code to get specific hour range for every Sunday for example: Every Sunday 10:50-12:35:
Entry.objects.filter(Record_Date__week_day=1,)
Record_Date__hour__gte=10)
Record_Date__hour__lte=12)
Record_Date__minute__gte=50)
Record_Date__minute__lte=35)
Do you have any idea for an alternative to do that?
__hour and __minute do not exist in django, yet your code would not be valid as 11:00 would be excluded.
I guess you will have to deal with __regex or raw SQL.
You could also just make two datetime objects, and filter(Record_Date__gte=start_datetime, Record_Date__lte=end_datetime).
It is confusing that Django doesn't choke, is Record_Date a ForeignKey to a model that has fields "minute", "hour" and "week_day" ?
I've got an app where users create pages. I want to run a simple DB query that returns how many users have created more than 2 pages.
This is essentially what I want to do, but of course it's not the right method:
User.objects.select_related('page__gte=2').count()
What am I missing?
You should use aggregates.
from django.db.models import Count
User.objects.annotate(page_count=Count('page')).filter(page_count__gte=2).count()
In my case, I didn't use last .count() like the other answer and it also works nice.
from django.db.models import Count
User.objects.annotate( our_param=Count("all_comments")).filter(our_param__gt=12)
use aggregate() function with django.db.models methods!
this is so useful and not really crushing with other annotation aggregated columns.
*use aggregate() at the last step of calculation, it turns your queryset to dict.
below is my code snippet using them.
cnt = q.values("person__year_of_birth").filter(person__year_of_birth__lte=year_interval_10)\
.filter(person__year_of_birth__gt=year_interval_10-10)\
.annotate(group_cnt=Count("visit_occurrence_id")).aggregate(Sum("group_cnt"))