Using Django's pre_delete signal for new object creation - django

Question

When a Tasks instance is deleted i want to create a new Instance of Completed Tasks, which stores the deleted task.
Here is my code -
from django.db import models
from django.db.models.signals import post_delete, pre_delete
from django.urls import reverse, reverse_lazy
from django.contrib.auth.models import User
class Tasks(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
TaskName = models.CharField(max_length=100)
Description = models.CharField(max_length=400)
DueDate = models.DateField(help_text="YYYY-MM-DD")
priority = models.IntegerField()
def __str__(self):
return self.TaskName
def get_absolute_url(self):
return reverse('tasks:detail', kwargs={'pk': self.pk})
pre_delete.connect(lambda instance,**kwargs:CompletedTasks.obbjects.create(task = instance))
class CompletedTasks(models.Model):
task = models.ForeignKey(Tasks, on_delete=None)
But , it is not working , instances of CompletedTasks are not being created.

Answer 1

You cannot have a foreign key reference to a non existent object, I suggest that you have a field in the Tasks model that keeps track of the status of the Task.
Something like this:
class Tasks(models.Model):
STATUSES = (
('C','Completed'),
('A', 'Active'),
)
user = models.ForeignKey(User, on_delete=models.CASCADE)
task_name = models.CharField(max_length=100)
description = models.CharField(max_length=400)
due_date = models.DateField(help_text="YYYY-MM-DD")
priority = models.IntegerField()
status = models.CharField(max_length=1, choices=STATUSES, default='A')