For example using made-up syntax: Entry.objects.create(start=F(Recurrence.objects.filter(pk=r_id), 'start_time'))
Note that we can't use `get` since the whole point is to avoid all the useless round-trips to the DB. Best, Casey On Thu, 21 Mar 2019 at 13:18, Dylan Young <[email protected]> wrote: > It's not a recalculation. It's instantiation. > > Instance data diverges from the factory data and needs to be independently > editable. > > Best, > > Casey > > Le jeu. 21 mars 2019 2:52 a.m., Derek <[email protected]> a écrit : > >> Permanently storing data that can be recalculated from existing data is a >> practice specific to the needs of particular applications. >> >> Have you perhaps considered making use of the "view" table functionality >> available in most databases? >> >> For example, in PostgreSQL you can create a materialized view which >> "caches the result of a complex expensive query and then allow you to >> refresh this result periodically." - see >> http://www.postgresqltutorial.com/postgresql-materialized-views/ >> >> >> On Tuesday, 19 March 2019 17:34:11 UTC+2, Dylan Young wrote: >>> >>> Hey all: >>> >>> I often find myself fetching data from models in the database only to >>> run a few trivial calculations and store the info in a different model. >>> >>> Is there an established ORM pattern for directly creating objects in the >>> DB based on the fields of other models? >>> >>> Sorry if this is obvious, but I couldn't find much on this in my web >>> searching. >>> >>> >>> Best, >>> >>> Casey >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at https://groups.google.com/group/django-users. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-users/a1c55adc-c5fa-465c-8740-3a741bc22686%40googlegroups.com >> <https://groups.google.com/d/msgid/django-users/a1c55adc-c5fa-465c-8740-3a741bc22686%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAPGJNu40H%3Du5bLLUYYosHpKNDsH7xMFPg-7GU%2B_fHCV59SknyA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
