Is the model definition correct in django - django

Question

I have defined below models in my models.py file.
I am trying to populate Allocation table only for the rows where member is null.
from django.db import models
from django.contrib.auth.models import User
# Create your models here.
class Member(models.Model):
user = models.OneToOneField(User, null=True, on_delete=models.CASCADE)
DESIGNATION = [
('Developer', 'Developer'),
('Tester', 'Tester'),
('Support', 'Support'),
]
name = models.CharField(max_length=200, null=True)
role = models.CharField(max_length=100, null=True, choices=DESIGNATION)
email = models.CharField(max_length=200, null=True)
date_created = models.DateTimeField(auto_now_add=True, null=True)
def __str__(self):
return self.name
class Task(models.Model):
CATEGORY = [
( 'Low', 'Low'),
('Medium', 'Medium'),
('Urgent', 'Urgent'),
]
STATUS = [
('Not Started', 'Not Started'),
('In Progress', 'In Progress'),
('Completed', 'Completed'),
]
name = models.CharField(max_length=200, null=True)
category = models.CharField(max_length=200, null=True, choices=CATEGORY)
description = models.CharField(max_length=200, null=True)
date_created = models.DateTimeField(auto_now_add=True, null=True)
member = models.ForeignKey('Member', null=True, on_delete=models.CASCADE)
task_status = models.CharField(max_length=200, null=True, choices=STATUS)
def __str__(self):
return self.name
class Allocation(models.Model):
member = models.ForeignKey('Member', null=True, on_delete=models.CASCADE)
task = models.OneToOneField('Task', null=True, on_delete=models.CASCADE)
date_created = models.DateTimeField(auto_now_add=True, null=True)
def __str__(self):
return self.task.name
And here is my view for task allocation
def allocate_task(request, pk):
task_details = Task.objects.get(id=pk)
form = TaskAllocateForm(instance=task_details)
if request.method == 'POST':
form = TaskAllocateForm(request.POST, instance=task_details)
if form.is_valid():
form.save()
return redirect('/')
forms.py:
class TaskAllocateForm(ModelForm):
class Meta:
model = Task
fields = ['name', 'member', 'task_status']
I am creating new tasks with create method which is working fine.
And I am trying to assign that task to a member from Member table.
But, the form.save() method in the allocate_task view is not reflecting changes in Allocation table