Django : 此数据库后端不支持 DISTINCT ON 字段

Question

如何修复 django 中的这个数据库后端不支持 DISTINCT ON 字段？

total = grade.objects.values('Grading_Categories').annotate(Average= Avg('Average')).filter(Teacher = m.id).distinct('Grading_Categories')

这是我的 model.py

class finalrating(models.Model):
Teacher = models.ForeignKey(EmployeeUser, related_name='+', on_delete=models.CASCADE,
null=True, blank=True)
Subjects = models.ForeignKey(Subject, related_name='+', on_delete=models.CASCADE, null=True)
Students_Enrollment_Records = models.ForeignKey(StudentsEnrolledSubject, related_name='+',
on_delete=models.CASCADE, null=True)
Average = models.FloatField(null=True, blank=True)
Status = models.CharField(max_length=500, null=True, choices=Pending_Request, blank=True)

我的问题来自这条线

total = grade.objects.values('Grading_Categories').annotate(Average= Avg('Average')).filter(Teacher = m.id).distinct('Grading_Categories')

Answer 1

我希望您正在尝试获得具有不同Grading_Categories值的GROUP BY结果。

所以，试试这个

total = grade.objects.values('Grading_Categories').annotate(Average=Avg('Average')).filter(Teacher=m.id).order_by('Grading_Categories')