django - Django 查询集中的计数和 OR 子句

Question

我有一个非常简单的查询，它没有按预期运行。

# Retrieve news                                                               
news = News.objects.filter(available=True)                                    
if area:                                                                      
    news = news.annotate(Count('areas')).filter(Q(areas__count=0)
                                                |Q(areas=area))

我希望有没有受影响区域或指定区域的新闻。但我一个都没有。

当我打印查询时，我得到：

SELECT "chimere_news"."id", "chimere_news"."title", 
       "chimere_news"."available","chimere_news"."date", "chimere_news"."content",
       COUNT("chimere_news_areas"."area_id") AS "areas__count"
FROM "chimere_news"
LEFT OUTER JOIN "chimere_news_areas" ON ("chimere_news"."id" = "chimere_news_areas"."news_id")
LEFT OUTER JOIN "chimere_news_areas" T4 ON ("chimere_news"."id" = T4."news_id")
WHERE ("chimere_news"."available" = True  AND (T4."area_id" = 1 ))
GROUP BY "chimere_news"."id", "chimere_news"."title", "chimere_news"."available", 
"chimere_news"."date", "chimere_news"."content"
HAVING COUNT("chimere_news_areas"."area_id") = 0

我做错了什么还是 Django 错误？

Answer 1

如果您只需要将计数与零进行比较，请尝试isnull改用。

if area:                                                                      
    news = news.filter(Q(areas__isnull=True)|Q(areas=area))