Opened 8 years ago

Closed 8 years ago

Last modified 8 years ago

#29422 closed Cleanup/optimization (invalid)

QuerySet.extra use case - "earth_box", "ll_to_earth"

Reported by: Mateusz Kurowski Owned by: nobody
Component: Database layer (models, ORM) Version: 2.0
Severity: Normal Keywords: QuerySet.extra, queryset, extra, earth_box, ll_to_earth, models, function, expression, manager
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

​https://docs.djangoproject.com/en/2.0/ref/models/querysets/#extra

This is my use case:

Code highlighting: 

class City(models.Model):
    longitude = models.FloatField(db_index=True)
    latitude = models.FloatField(db_index=True)

# this works:
City.objects.extra(where=['earth_box(ll_to_earth(%s,%s), %s) @> ll_to_earth(latitude, longitude)'], params=[51.41816, 15.90689, 500000])
# this does not:
City.objects.extra(where=['earth_box(ll_to_earth(%s,%s), %s) @> ll_to_earth(latitude, longitude)'], params=[F('latitude'), F('longitude'), 50000])
# psycopg2.ProgrammingError: can't adapt type 'F'

I could rewrite this in a custom Manager, but how?

Change History (2)

comment:1 by Shai Berger, 8 years ago

Resolution: → invalid
Status: new → closed

Without going into too many details, I'd expect you to be able to define two ​user functions (something like LLToBox() taking two arguments and LLToEarthBox() taking three) and use the builtin contains comparison, or, if this doesn't work, define your own ​comparison.

In general, please direct such questions to the available help channels. I am closing this ticket as invalid, for more details see TicketClosingReasons/UseSupportChannels.

comment:2 by Mateusz Kurowski, 8 years ago

@Shai Berger how i can use contains? Can you show an example queryset, how you see it?

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