这是一个孤立的 ORM 查询:
Purpose.objects.annotate(
conversation_count=SubqueryCount(
Conversation.objects.filter(goal_slugs__contains=[OuterRef("slug")]).values("id")
)
)
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其中 SubqueryCount 是:
from django.db.models import IntegerField
from django.db.models.expressions import Subquery
class SubqueryCount(Subquery):
template = "(SELECT count(*) FROM (%(subquery)s) _count)"
output_field = IntegerField()
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运行该查询时,将使用以下 sql(通过 djdt 解释):
SELECT
"taxonomy_purpose"."id",
"taxonomy_purpose"."slug",
(
SELECT count(*)
FROM (
SELECT U0."id"
FROM "conversations_conversation" U0
WHERE U0."goal_slugs" @> ARRAY['ResolvedOuterRef(slug)']::varchar(100)[]
) _count
) AS "conversation_count"
FROM "taxonomy_purpose"
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注意ResolvedOuterRef(slug)作为字符串注入到 ARRAY 查找中。我做错了什么,还是应该将此报告为错误?如果这是一个错误,是否有已知的解决方法(可能创建自定义 OuterRef 类)?