Question

我有两个模型类和一个Through类：

class Terms(models.Model):
    name = models.CharField(max_length=64)
    posts = models.ManyToManyField("Post", through="TermRelation")

class Post(models.Model):
    title = models.CharField(max_length=120)
    content = models.TextField()
    published_on = models.DateTimeField(auto_now_add=True)

    # Categories and Tags
    terms = models.ManyToManyField("Term", through="TermRelation")

class TermRelation(models.Model):
    class Meta:
        db_table = "tbl_term_relation"
        unique_together = (
            ("term", "term_type", "post"),
        )

    CITES = (
        ('CAT', 'Category'),
        ('TAG', 'Tag'),
    )

    term = models.ForeignKey(Term, db_column="id_term")
    post = models.ForeignKey(Post, db_column="id_post")
    term_type = models.CharField('Term Type', max_length=3,
                                 default=CITES[0][0], choices=CITES)

在这里，我只想选择类别Java中的那些类型的帖子。

所以，我这样做，但这是例外：

Post.objects.filter(terms__name='Java', termrelation_set__term_type='CAT')

正如SQL Expect：

SELECT ... FROM Post p
LEFT OUTER JOIN TermRelation r ON p.id = r.id_post
LEFT OUTER JOIN Term t ON t.id = r.id_term
WHERE r.term_type = 'CAT'
      AND t.name = 'Java';

请帮助我，我该怎么办？

Answer 1

而不是termrelation_set__term_type，请尝试termrelation__term_type。从official documentation -

获取提示

As you are using an intermediate model, you can also query on its attributes:

# Find all the members of the Beatles that joined after 1 Jan 1961
>>> Person.objects.filter(
...     group__name='The Beatles',
...     membership__date_joined__gt=date(1961,1,1))
[<Person: Ringo Starr]

Django模型如何通过模型字段添加过滤条件

1 个答案: