筛选满足一组条件的多对多关系 [英] Filtering on many-to-many relations that fulfill a set of criteria

问题描述

使用以下型号:

class OrderOperation(models.Model):
    ordered_articles = models.ManyToManyField(Article,
                                              through='orders.OrderedArticle')

class OrderedArticle(models.Model):
    order_operation = models.ForeignKey(OrderOperation)
    article = models.ForeignKey(Article)

articles = ... # some queryset containing multiple articles

如果我要查找包含至少一篇文章的订单操作，则可以按预期工作:

If I want to find order operations containing at least one article, this works as expected:

OrderOperation.objects.filter(ordered_articles__in=articles)

但是，如果我想查找订单中所有商品的订单操作，正确的方法是什么?

However, if I want to find order operations with all the articles in the order, what is the correct way to do it?

OrderOperation.objects.filter(ordered_articles=articles)引发ProgrammingError: more than one row returned by a subquery used as an expression错误(我理解为什么会这样).

OrderOperation.objects.filter(ordered_articles=articles) raises a ProgrammingError: more than one row returned by a subquery used as an expression error (I understand why actually).

推荐答案

一个简单的解决方案:

order_operations = OrderOperation.objects.all()
for article in articles:
    order_operations = order_operations.filter(ordered_articles=article)

这只是一个查询，但每篇文章都有一个内部联接.对于不止几篇文章，Willem更巧妙的解决方案应该会表现更好.

It's just one query, but with an inner join per article. For more than a few articles Willem’s more ingenious solution should perform better.

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