Value Error:Cannot assign queryset to attribute it must be instance - django

Question

I have models.py
class employees(models.Model):
emp_id=models.PositiveIntegerField()
emp_name = models.CharField(max_length = 100)
emp_lname = models.CharField(max_length = 100)
emp_loc=models.CharField(max_length=5,choices=LOCATION)
manager_id=models.ForeignKey('self',null=True,blank=True)
class leave(models.Model):
employee = models.ForeignKey(employees, on_delete=models.CASCADE, default='1')
start_date = models.DateField()
end_date = models.DateField()
status=models.CharField(max_length=1,choices=LEAVE_STATUS,default='P')
ltype=models.CharField(max_length=2,choices=LEAVE_TYPE)
message=models.CharField(max_length=500,blank=True)
class notify(models.Model):
sender_id=models.ForeignKey(leave, related_name='%(class)s_sendername')
receiver_id=models.ForeignKey(leave,related_name='%(class)s_receivername')
date_time=models.DateTimeField()
I have views.py
def accept(request):
approved_emp_id=leave.objects.filter(id=accept_id);
approving_emp_id=leave.objects.filter(employee__emp_id=request.user.username);
accept_notify=notify(sender_id=approving_emp_id, receiver_id=approved_emp_id,date_time=datetime.datetime.now(),viewed='N');
accept_notify.save()
When I want to save values to database I am getting error as ValueError: Cannot assign "<QuerySet [<leave: 121-geeta-2017-10-04-2017-10-06-C-V-2017-09-27 07:48:36.288873+00:00>]>": "notify.sender_id" must be a "leave" instance.
Where am I going wrong approving_emp_id and approved_emp_id are both leave instance only.

Answer 1

You are passing a QuerySet when the arguments should be an instance. A QuerySet is a list of instances. Pass only one instance. Use leave.objects.get() instead of leave.objects.filter().
objects.get() returns a single instance where objects.filter() returns a QuerySet.
def accept(request):
approved_emp_id = leave.objects.get(id = accept_id)
approving_emp_id = leave.objects.get(employee__emp_id = request.user.username)
accept_notify = notify(sender_id = approving_emp_id, receiver_id = approved_emp_id, date_time = datetime.datetime.now(), viewed = 'N')
accept_notify.save()
Another way is slicing the QuerySet.
def accept(request):
approved_emp_id = leave.objects.filter(id = accept_id)[0]
approving_emp_id = leave.objects.filter(employee__emp_id = request.user.username)[0]
accept_notify = notify(sender_id = approving_emp_id, receiver_id = approved_emp_id, date_time = datetime.datetime.now(), viewed = 'N')
accept_notify.save()