InMemoryFileNode object has no attribute "name"

[David]

Using the InMemoryStorage into an other model by using:

# models.py

class MyModel(models.Model):
    attachment = models.FileField(...)

# script.py

obj = MyModel.objects.create(attachment=ContentFile(b'content', 'myfile.txt') 
repr(obj.attachment)

An excetption is raised: AttributeError("'InMemoryFileNode' object has no attribute 'name'") raised in repr()

This may be caused by the fact that InMemoryFileNode inheriths from ContentFile but does not use the name attribute nor uses the base class __init__ method:

​https://github.com/django/django/blob/509763c79952cde02d9f5b584af4278bdbed77b2/django/core/files/storage/memory.py#L48-L52

This resulting in a partially initialized object without an important property.

[Lucas Esposito]

I agree about the need of the issue. I also found other places were the 'name' attribute may be accessed, which would result in a similar error as described above.

I just made a PR: ​https://github.com/django/django/pull/18453

[Sarah Boyce]

Hi David, I have not been able to replicate the error on main or Django 4.2

@override_settings(
    STORAGES={"default": {"BACKEND": "django.core.files.storage.InMemoryStorage"}}
)
class FileFieldModelTest(TestCase):
    def test_repr(self):
        test = FileFieldModel.objects.create(
            file=ContentFile(b'content', 'myfile.txt')
        )
        self.assertEqual(repr(test.file), "<FieldFile: myfile.txt>")

Can you share the full traceback or give more instructions on how to replicate the error?

[Sarah Boyce]

Ah I found an error

@override_settings(
    STORAGES={"default": {"BACKEND": "django.core.files.storage.InMemoryStorage"}}
)
class FileFieldModelTest(TestCase):
    def test_repr(self):
        test = FileFieldModel()
        test.file.save(None, ContentFile(b'content', 'myfile.txt'))
        self.assertEqual(repr(test.file), "<FieldFile: myfile.txt>")

Breaks with

Traceback (most recent call last):
  File "test-django-package/mysite/app3/tests.py", line 13, in test_repr
    test.file.save(None, ContentFile(b'content', 'myfile.txt'))
  File "test-django-package/venv/lib/python3.10/site-packages/django/db/models/fields/files.py", line 92, in save
    name = self.field.generate_filename(self.instance, name)
  File "test-django-package/venv/lib/python3.10/site-packages/django/db/models/fields/files.py", line 335, in generate_filename
    filename = posixpath.join(dirname, filename)
  File "/usr/lib/python3.10/posixpath.py", line 90, in join
    genericpath._check_arg_types('join', a, *p)
  File "/usr/lib/python3.10/genericpath.py", line 152, in _check_arg_types
    raise TypeError(f'{funcname}() argument must be str, bytes, or '
TypeError: join() argument must be str, bytes, or os.PathLike object, not 'NoneType'

[Sarah Boyce]

Still don't get the error as reported in the ticket so further details would be welcome

[David]

Replying to Sarah Boyce:

Still don't get the error as reported in the ticket so further details would be welcome

Sorry I have miss-interpreted a stack trace of an other error coming from pytest and pasted the wrong part

The stacktrace frame showed up

instance   = <[AttributeError("'InMemoryFileNode' object has no attribute 'name'") raised in repr()] MyModel

Because the model uses attachment.name in its __str__ method.

Whatching back the behaviour now I have isolated a test which fails:

obj = MyModel.objects.create(attachment=ContentFile(b'content', 'myfile.txt'))
obj2 = MyModel.objects.create(attachment=obj.attachment.file)

Which raises the following stacktrace:

Traceback (most recent call last):
  File "<workspace>/db_35658/db_35658/tests.py", line 24, in test_copy_file
    obj2 = MyModel.objects.create(attachment=obj.attachment.file)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/manager.py", line 87, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/query.py", line 658, in create
    obj.save(force_insert=True, using=self.db)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/base.py", line 814, in save
    self.save_base(
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/base.py", line 877, in save_base
    updated = self._save_table(
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/base.py", line 1020, in _save_table
    results = self._do_insert(
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/base.py", line 1061, in _do_insert
    return manager._insert(
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/manager.py", line 87, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/query.py", line 1805, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1821, in execute_sql
    for sql, params in self.as_sql():
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1745, in as_sql
    value_rows = [
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1746, in <listcomp>
    [
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1747, in <listcomp>
    self.prepare_value(field, self.pre_save_val(field, obj))
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1695, in pre_save_val
    return field.pre_save(obj, add=True)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/fields/files.py", line 314, in pre_save
    file = super().pre_save(model_instance, add)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/fields/__init__.py", line 932, in pre_save
    return getattr(model_instance, self.attname)
  File "<workspace>/db_35658/.venv/lib/python3.10/site-packages/django/db/models/fields/files.py", line 200, in __get__
    file_copy = self.field.attr_class(instance, self.field, file.name)
AttributeError: 'InMemoryFileNode' object has no attribute 'name'

[Sarah Boyce]

Thank you for the follow up David - that helped a lot!

[Sarah Boyce <42296566+sarahboyce@…>]

In f16a9a55:

Fixed #35658 -- Initialized InMemoryFileNode instances with a name.

[Sarah Boyce <42296566+sarahboyce@…>]

In a57596e:

Refs #35658 -- Fixed test_create_file_field_from_another_file_field_in_memory_storage when run in reverse.