title: Value Error:Cannot assign queryset to attribute it must be instance
body: <p>I have models.py</p>
  
  <pre><code>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()
  </code></pre>
  
  <p>I have views.py</p>
  
  <pre><code> 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()
  </code></pre>
  
  <p>When I want to save values to database I am getting error as <code>ValueError: Cannot assign "&lt;QuerySet [&lt;leave: 121-geeta-2017-10-04-2017-10-06-C-V-2017-09-27 07:48:36.288873+00:00&gt;]&gt;": "notify.sender_id" must be a "leave" instance.</code></p>
  
  <p>Where am I going wrong <code>approving_emp_id</code> and <code>approved_emp_id</code> are both leave instance only.</p>