Django 'NoneType' object has no attribute 'obj'

Question

I know there are a few posts about this very same problem but the solution is to be found in some error made in the code that I can't figure out. So I'm posting here what I have written so far, hoping for your help. I have a class Node and I get the error stated in the title when I perform a POST. This is my code:

class NodeResource(ModelResource):

class Meta:
    queryset = api.models.Node.objects.all()
    resource_name = _Helpers.node_resource_name
    always_return_data = True

    # Allow retrieving large quantities of nodes at once.
    limit = 250
    max_limit = 0

    filtering = {'name', 'is_ulg', 'latitude', 'longitude'}
    allowed_methods = ['get', 'post']
    authentication = Authentication()
    authorization = Authorization()

def obj_create(self, bundle, **kwargs):
    node = api.models.Node(name=bundle.data['name'],
                           is_ulg=bundle.data['is_ulg'],
                           latitude=bundle.data.get("latitude"),
                           longitude=bundle.data.get("longitude"))
    node.save()

The model is the following:

class Node(models.Model):
"""
Represents a node in the graph.
"""
name = models.CharField(max_length=255)
is_ulg = models.BooleanField(default=False, verbose_name='Is this node a member of the ULg?')

latitude = models.FloatField()
longitude = models.FloatField()

def __str__(self):
    return self.name

class Meta:
    ordering = ['name']
    unique_together = ("latitude", "longitude") 

When I perform a post with the following json

{"name":"Node name","latitude": "2.4567", "longitude":"2.345", "is_ulg":false}

The node is correctly created, but I always get the error stated in the title. The full error is the following:

{"error_message":"'NoneType' object has no attribute 'obj'","traceback":"Traceback (most recent call last):\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/resources.py\", line 202, in wrapper\n    response = callback(request, *args, **kwargs)\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/resources.py\", line 433, in dispatch_list\n    return self.dispatch('list', request, **kwargs)\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/resources.py\", line 465, in dispatch\n    response = method(request, **kwargs)\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/resources.py\", line 1347, in post_list\n    updated_bundle = self.full_dehydrate(updated_bundle)\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/resources.py\", line 853, in full_dehydrate\n    bundle.data[field_name] = field_object.dehydrate(bundle, for_list=for_list)\n\n  File \"\/usr\/lib\/python2.7\/site-packages\/tastypie\/fields.py\", line 116, in dehydrate\n    current_object = bundle.obj\n\nAttributeError: 'NoneType' object has no attribute 'obj'\n"}

Any idea what I'm doing wrong? Thanks!

Answer 1

Your object_create function is implicitly returning None, but Tastypie is expecting it to return a bundle. See how it is implemented in the docs example.

However, since it doesn't seem like you're using non-ORM data, you could just skip obj_create and let Tastypie create the resource for you.