从外键的另一侧接近模型

发布于 2024-09-26 11:14:49 字数 406 浏览 6 评论 0原文

使用Django 文档示例博客和 Entry 模型，如何获取所有具有 name = "a" 并且不与任何实例关联的 Blog 对象的查询集Entry 模型的？

用原始 (My)SQL 术语来说，Django ORM 相当于：

SELECT * FROM blog_table bt
WHERE bt.name='a' AND bt.id NOT IN (SELECT et.blog_id FROM entry_table et)

原文

Working with Django docs' sample Blog and Entry models, how would one get a queryset of all Blog objects that have name = "a" and that are not associated with any instance of the Entry model?

In raw (My)SQL terms, what is the Django ORM equivalent of:

SELECT * FROM blog_table bt
WHERE bt.name='a' AND bt.id NOT IN (SELECT et.blog_id FROM entry_table et)

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北方的韩爷 2024-10-03 11:14:49

您需要的是具有 name = "a" 并且没有任何关联条目的 Blog 实例列表。您可以通过以下方式执行此操作：

Blog.objects.filter(name = "a", entry = None)
#                   ^^^^        ^^^^^
#           <Match name>        <Should have no associated Entry instances>

What you need is a list of Blog instances that have name = "a" and do not have any associated entries. You can do this by:

Blog.objects.filter(name = "a", entry = None)
#                   ^^^^        ^^^^^
#           <Match name>        <Should have no associated Entry instances>

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