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@arthuralvim

arthuralvim/example.py

Forked from bblanchon/example.py
Created December 19, 2022 23:05
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  1. @bblanchon bblanchon created this gist Apr 9, 2021.
    7 changes: 7 additions & 0 deletions example.py
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    Original file line number Diff line number Diff line change
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    from django.db.models import OuterRef

    weapons = Weapon.objects.filter(unit__player_id=OuterRef('id'))
    units = Unit.objects.filter(player_id=OuterRef('id'))

    qs = Player.objects.annotate(weapon_count=SubqueryCount(weapons),
    rarity_sum=SubquerySum(units, 'rarity'))
    20 changes: 20 additions & 0 deletions subquery_aggregate.py
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    class SubqueryCount(Subquery):
    # Custom Count function to just perform simple count on any queryset without grouping.
    # https://stackoverflow.com/a/47371514/1164966
    template = "(SELECT count(*) FROM (%(subquery)s) _count)"
    output_field = PositiveIntegerField()


    class SubqueryAggregate(Subquery):
    # https://code.djangoproject.com/ticket/10060
    template = '(SELECT %(function)s(_agg."%(column)s") FROM (%(subquery)s) _agg)'

    def __init__(self, queryset, column, output_field=None, **extra):
    if not output_field:
    # infer output_field from field type
    output_field = queryset.model._meta.get_field(column)
    super().__init__(queryset, output_field, column=column, function=self.function, **extra)


    class SubquerySum(SubqueryAggregate):
    function = 'SUM'