python - Django How to make only one query with queryset exists method? -


i try understand django documentation queryset exists method

additionally, if some_queryset has not yet been evaluated, know @ point, using some_queryset.exists() more overall work (one query existence check plus 1 later retrieve results) using bool(some_queryset), retrieves results , checks if returned.

what i'm doing:

    if queryset.exists():         do_something()          element in queryset:             do_something_else(element)

so i'm doing more overall work using bool(some_queryset)

does code makes 1 query?

    if bool(queryset):         do_something()          element in queryset:             do_something_else(element)

if yes python puts results ? in queryset variable ?

thank you

from .exists() docs itself:

additionally, if some_queryset has not yet been evaluated, know @ point, using some_queryset.exists() more overall work (one query existence check plus 1 later retrieve results) using bool(some_queryset), retrieves results , checks if returned.

the results of evaluated queryset cached django. so, whenever data required queryset cached results used.

related docs: caching , querysets


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