title: 'update_grid' object has no attribute 'title'
body: <p>I have written model.py and views.py.When I add the json variable from Admin it gives following error</p>
  
  <p><code>'update_grid' object has no attribute 'title'</code></p>
  
  <p>My views.py </p>
  
  <pre><code>def save_grid(request):
      if request.method == 'POST':
              data = json.loads(request.body)
              grid = update_grid(data=data)
              grid.save()
              return HttpResponse('success') # if everything is OK
  </code></pre>
  
  <p>My models.py </p>
  
  <pre><code>from django.db import models
  from django.utils import timezone
  from jsonfield import JSONField
  
  
  
  class update_grid(models.Model):
      data = JSONField()
  
      def __str__(self):
          return self.title
  </code></pre>
  
  <p>My JSON variable is of the form </p>
  
  <pre><code> [{"col":1,"row":1,"size_x":1,"size_y":1},{"col":2,"row":1,"size_x":1,"size_y":1},{"col":3,"row":1,"size_x":1,"size_y":1},{"col":4,"row":1,"size_x":1,"size_y":1},{"col":1,"row":2,"size_x":1,"size_y":1},{"col":2,"row":2,"size_x":1,"size_y":1},{"col":3,"row":2,"size_x":1,"size_y":1},{"col":4,"row":2,"size_x":1,"size_y":1},{"col":1,"row":3,"size_x":1,"size_y":1},{"col":2,"row":3,"size_x":1,"size_y":1},{"col":3,"row":3,"size_x":1,"size_y":1},{"col":4,"row":3,"size_x":1,"size_y":1},{"col":5,"row":1,"size_x":1,"size_y":1},{"col":6,"row":1,"size_x":1,"size_y":1}] 
  </code></pre>