Question

我有以下型号

class SchoolClass(models.Model):
    id = models.AutoField(primary_key = True)
    class_name = models.TextField()
    level = models.IntegerField()
    taught_by = models.ManyToManyField(User,related_name="teacher_teaching",through='TeachSubject')
    attended_by = models.ManyToManyField(User,related_name='student_attending')

    def __unicode__(self):
        return self.class_name
    class Meta:
        db_table = 'classes'

class Relationship(models.Model):
    rChoices = (
        (1,'Mother'),
        (2,'Father'),
        (3,'Guardian'),
    )

    parent = models.ForeignKey(User,related_name='parent')
    student = models.ForeignKey(User,related_name='child')
    relationship = models.IntegerField(choices= rChoices)
    #add in __unicode__ for admin name

    class Meta:
        unique_together = ('parent','student')
        db_table = 'relationship

我有班级的PK，我想找出谁是所选班级学生的家长。

我的微弱尝试是：

selected_class =  SchoolClass.objects.get(pk=class_id)
studs = selected_class.attended_by.all().select_related()
r = Relationship.objects.filter(student__in=students)

parents = [.parent for p in r]

现在，我只是好奇是否有更短或更有效的方法（我肯定错过了文档中的内容）？

Answer 1

这应该有效

parents = Relationship.objects.filter(student__schoolclass__id=class_id).values_list('parent', flat=True)

“要引用”反向“关系，只需使用模型的小写名称”。（docs）

django在模型中访问外键

1 个答案: