关于Django：在表上插入或更新违反外键约束(错误)

Insert or update on table violates foreign key constraint (error)

我正在尝试将表单数据保存到Postgres表\\'Student_Events \\'中，该表通过外键链接到\\'Student_INFO表\\'，但继续收到完整性错误：

\\'在表" entry_student_event "上插入或更新违反了外键约束" entry_student_event_nsn_id_2499e7fd_fk_entry_student_info_id "
详细信息：表" entry_student_info "中不存在键(nsn_id)=(123556789)。\\'

Student_INFO中有一个学生的nsn为\\'123556789 \\'，因此我不确定在该表中为什么它"不存在"。任何帮助将不胜感激，因为我对Django和PostgresSQL还是很陌生，
谢谢

Views.py：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

def Grouplist(request):
student_list = Student_INFO.objects.order_by('name')

FOR student IN student_list:
IF request.method == 'POST':
form = EntryForm(request.POST)
context = {
'student_list':student_list,
'form': form
}
IF form.is_valid():
event_save = form.save(commit=FALSE)
event_save.nsn_id = student.nsn
event_save.save()
RETURN redirect('grouplist')
ELSE:
form = EntryForm()
context = {
'student_list':student_list,
'form': form
}
RETURN render(request, 'grouplist.html', context)

Models.py：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

class Student_INFO(models.Model):
nsn = models.IntegerField(blank = FALSE)
birthdate = models.DateField("BirthDate", blank = FALSE)
name = models.CharField(max_length=30, blank = FALSE)
age_catagory = models.CharField(max_length=8, blank = TRUE, DEFAULT = '')
grouproom = models.CharField(max_length=3, blank = FALSE)
year_lvl = models.IntegerField(blank = FALSE)
created = models.DateTimeField(auto_now_add=TRUE)
updated = models.DateTimeField(auto_now=TRUE)

def __str__(SELF):
RETURN SELF.name

class Student_Event(models.Model):
nsn = models.ForeignKey(Student_INFO, on_delete=models.CASCADE)
event1 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')
event2 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')
event3 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')
event4 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')
event5 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')
event6 = models.CharField(max_length=15, blank=FALSE, DEFAULT = '')

def __str__(SELF):
RETURN SELF.nsn

Forms.py

1
2
3
4
5
6
7
8
9
10
11
12

class EntryForm(forms.ModelForm):
class Meta:
model= Student_Event
FIELDS= ["event1","event2","event3","event4","event5","event6"]
widgets = {
'event1':forms.Select(choices=EVENT_CHOICES),
'event2':forms.Select(choices=EVENT_CHOICES),
'event3':forms.Select(choices=EVENT_CHOICES),
'event4':forms.Select(choices=EVENT_CHOICES),
'event5':forms.Select(choices=EVENT_CHOICES),
'event6':forms.Select(choices=OPEN_CHOICES),
}

返回错误：

1 2	INSERT OR UPDATE ON TABLE"entry_student_event" violates FOREIGN KEY CONSTRAINT"entry_student_event_nsn_id_2499e7fd_fk_entry_student_info_id" DETAIL: KEY (nsn_id)=(123556789) IS NOT present IN TABLE"entry_student_info".