You can’t use python functions for annotations. Annotation is a computation that is done on a database level. Django provides you only a set of basic computations which can be processed by the database – SUM, AVERAGE, MIN, MAX and so on… For more complex stuffs only from version 1.8 we have an API for … Read more
I would prefer to use the Q object for something like this. from django.db.models import Q keyword = ‘keyword’ fields = [‘foo’, ‘bar’, ‘baz’] Qr = None for field in fields: q = Q(**{“%s__contains” % field: keyword }) if Qr: Qr = Qr | q # or & for filtering else: Qr = q # … Read more
this line of code at = AttachedInfo.objects.filter(attachedMarker=m.id, title=title) returns a queryset and you are trying to access a field of it (that does not exist). what you probably need is at = AttachedInfo.objects.get(attachedMarker=m.id, title=title)
One of the problems with your example is that you cannot use queryset.count() as a subquery, because .count() tries to evaluate the queryset and return the count. So one may think that the right approach would be to use Count() instead. Maybe something like this: Post.objects.annotate( count=Count(Tag.objects.filter(post=OuterRef(‘pk’))) ) This won’t work for two reasons: The … Read more
Yes, I think you want make = Make.objects.get(pk=1) make.make_content_set.filter(published=True) or maybe make_ids = MakeContent.objects.filter(published=True).values_list(‘make_id’, flat=True) makes = Make.objects.filter(id__in=make_ids)
from django.db.models import Q User.objects.filter(Q(income__gte=5000) | Q(income__isnull=True)) via Documentation
F objects. from django.db.models import F stale_activities = Activity.objects.filter(updated__gte=F(‘added_toSolr_date’))
Although the Django docs recommend using count rather than len: Note: Don’t use len() on QuerySets if all you want to do is determine the number of records in the set. It’s much more efficient to handle a count at the database level, using SQL’s SELECT COUNT(*), and Django provides a count() method for precisely … Read more
I would focus on the example queries rather than your quote from the documentation. Aggregate calculates values for the entire queryset. Annotate calculates summary values for each item in the queryset. Aggregation >>> Book.objects.aggregate(average_price=Avg(‘price’)) {‘average_price’: 34.35} Returns a dictionary containing the average price of all books in the queryset. Annotation >>> q = Book.objects.annotate(num_authors=Count(‘authors’)) >>> … Read more
This should work (using the same MySQL specific function you used): Review.objects.filter(venue__pk=2) .extra({‘date_created’ : “date(datetime_created)”}) .values(‘date_created’) .annotate(created_count=Count(‘id’))