How to point django form to pk? - django

Question

I am trying to make a form that is dynamically selected by a DetailView object.
I want to click the DetailView link and be taken to a form whose primary key is the same as the primary key from my detail view. When I attempt to do this I get an error. How can I do this? Is their a prebuilt library that will assist me?
My Model:
'''
class MemberStudent(models.Model):
instructor = models.ForeignKey(Teachers, on_delete=models.CASCADE)
name = models.CharField(max_length=50, default="Doe")
age = models.IntegerField(default=99)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse('student_detail', args=[str(self.id)])
class BehaviorGrade(models.Model):
SEVERITY = [
('Bad','Bad Behavior'),
('Good','Good Behavior'),
('Danger','Dangerous'),
]
LETTER_GRADE = [
('A','A'),
('B','B'),
('F','F'),
]
studentName = models.ForeignKey(MemberStudent, on_delete=models.CASCADE) #need a link to student name
eventGrade = models.CharField(max_length=1, choices=LETTER_GRADE)
eventSeverity = models.CharField(max_length=15, choices=SEVERITY)
eventTitle = models.CharField(max_length=15)
eventDescription = models.TextField()
def __str__(self):
return self.eventTitle
'''
My Views:
'''
class StudentDetailView(FormMixin,DetailView):
model = MemberStudent
template_name = 'student_detail.html'
form_class = BehaviorForm
def get_success_url(self):
return reverse('student_detail', kwargs={'pk':self.object.pk})
def post(self, request, *args, **kwargs):
self.object = self.get_object()
form = self.get_form()
if form.is_valid():
form.save()
return self.form_valid(form)
else:
return self.form_invalid(form)
def form_valid(self, form):
return super().form_valid(form)
'''
my forms.py:
'''
class BehaviorForm(ModelForm):
class Meta:
model = BehaviorGrade
fields = ['eventGrade',
'eventSeverity','eventTitle',
'eventDescription']
'''
my url:
'''
path('students/<int:pk>', StudentDetailView.as_view(), name='student_detail'),
'''
my htmltemplate(its a detailview with a form below on the same page):
'''
{{ object.id }}
{{ object.name }}
{{ object.age }}
{{ object.instructor }}
<form action="{% url 'student_detail' object.id %}" method="POST">
{{ form }}
{% csrf_token %}
<input type="submit" value="REVIEW">
</form>
'''
error message when form submitted:
"IntegrityError at /student/students/1
NOT NULL constraint failed: Students_behaviorgrade.studentName_id"
The form also is sent without the PK I have requested in my form code.
the django error log shows the PK is never sent
here is the log message on a test of dummy data:
params [None, 'A', 'Bad', 'asdf', 'asdf']

Answer 1

That's because you have to manually set the member student id on the behavior garde.
You can do it like this in the post function of your view :
def post(self, request, *args, **kwargs):
self.object = self.get_object()
form = self.get_form()
if form.is_valid():
behavior_grade = form.save(commit=False)
behavior_grade.studentName = self.object
return self.form_valid(form)
else:
return self.form_invalid(form)
You can also take a look at this method to use the form_valid function to do it :
## Include the instance object before saving
def form_valid(self, form):
form.instance.studentName = self.object
return super().form_valid(form)

Answer 2

The solution was to to call the primary key in the model method. Then to save to the correct model object I called .pk on my object. I'm cannot elegantly explain this solution however upon testing several different scenarios it works.
'''
def post(self, request, *args, **kwargs):
self.object = self.get_object()
form = self.get_form()
if form.is_valid():
behavior_grade = form.save(commit=False)
behavior_grade.studentName = self.object #passes unamed form field
behavior_grade.studentName.pk = form.save(commit=True) #calls key
return self.form_valid(form)
else:
return self.form_invalid(form)
'''