如何在 django 信号 post_save 中使用 update_fields

Question

I hope my title is enough to understant what i am trying to say if not then sorry in advance.

I dont have problem on inserting data, but how about when the admin update the section of student were the student have already record?, I just want to update the current data not add another data

this is my code in my model.py(post_save)..

@receiver(post_save, sender=StudentsEnrollmentRecord)
def create(sender, instance, created, **kwargs):
    teachers = SubjectSectionTeacher.objects.filter(Courses=instance.Courses, Sections=instance.Section)
    if created and teachers.exists():
        StudentsEnrolledSubject.objects.create(
            # This should be the instance not instance.Student_Users
            Students_Enrollment_Records=instance,
            # The below is also not an instance of SubjectSectionTeacher
            Subject_Section_Teacher=teachers.first())

Answer 1

Your code has other problems (why are you using CamelCase for attributes?), but in Django if you want to conditionally create a new object, you can use update_or_create() . Example:

StudentsEnrolledSubject.objects.update_or_create(
        pk=instance.pk, defaults={"enrollment_credits": enrollment_credits}
)

This will create a new StudentsEnrolledSubject object if instance.pk does not exist in the database. Otherwise, it will update the existing instance's enrollment_credits .