0 
// signals.py

@receiver(pre_save, sender=AcademicLesson)
def take_attendance(sender, instance, **kwargs):
    new_file = instance.class_img
    if new_file:
        sub = instance.sub_id
       
        # this for loops gives all student from each branch having comman subject(sub = instance.sub_id)
        for branch in sub.universitybranch_set.all():
            for std in branch.studentprofile_set.all():
                if std.profile_encode: # for understanding, student present or not
                    print('-------------------------added')
                    instance.student.add(std)
                else:
                    print('---------------------not-added')
        print('no. of student=', len(instance.student.all()))

# // models.py

class AcademicLesson(models.Model):

    date = models.DateField()
    sub_id = models.ForeignKey('UniversitySubject', on_delete=models.CASCADE, limit_choices_to={'is_elect': True})
    class_type = models.CharField(max_length=7, choices=[('lecture','Lecture'),('lab','Lab')])
    slot = models.CharField(max_length=1, choices=[('1','1'),('2','2'),('3','3'),('4','4'),('5','5'),('6','6')])
    class_img = models.ImageField(upload_to=path_to_upload_media, blank=True)
    student = models.ManyToManyField('StudentProfile', blank=True)

    def __str__(self):
        return f"{self.date} | {self.sub_id}"
    class Meta: 
        verbose_name = 'Academic Lesson'

我从管理面板提交的表格

调试控制台看起来像

当我用 django shell 验证时，它返回 <QuerySet []>

lesson = AcademicLesson.objects.get(date='2021-04-05')
lesson.student.all()

我尝试了什么。

  1. 覆盖 models.Model.save 方法，但会出现同样的问题。
  2. forms.ModelForm 不适合我们的项目

如果我在 django shell 中运行 signals.py 中显示的代码，那么它可以正常工作，但是相同的逻辑在 signals.py 中不起作用

我哪里做错了？

4

0 回答 0