异常值：“ NoneType”对象没有属性“ rfind”

Question

My code throws me an exception but Googling hasnt helped me. I did an error check on it possibly could be it getting the wrong path, but it prints the correct one out to the console.

Exception Value:

'NoneType' object has no attribute 'rfind'

def user_directory_path(instance, filename):
    time_stamp = 'user_{0}/{1}'.format(instance.user, filename)
    createfolder = os.path.join('home', 'ttt', 'Desktop', 'GolemProject', 'Fileuploads', time_stamp,)
    print(createfolder)
    if not os.path.exists(createfolder):
        os.makedirs(createfolder)

From the console:

home/ttt/Desktop/GolemProject/Fileuploads/user_wqe/vbbfgsfdgfds.zip
Internal Server Error: /callgolem/
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/exception.py", line 35, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/ttt/Desktop/GolemProject/callgolem/views.py", line 65, in index
    instance.save()
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/base.py", line 729, in save
    force_update=force_update, update_fields=update_fields)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/base.py", line 759, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/base.py", line 842, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/base.py", line 880, in _do_insert
    using=using, raw=raw)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/query.py", line 1125, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/compiler.py", line 1283, in execute_sql
    for sql, params in self.as_sql():
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/compiler.py", line 1236, in as_sql
    for obj in self.query.objs
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/compiler.py", line 1236, in <listcomp>
    for obj in self.query.objs
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/compiler.py", line 1235, in <listcomp>
    [self.prepare_value(field, self.pre_save_val(field, obj)) for field in fields]
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/sql/compiler.py", line 1185, in pre_save_val
    return field.pre_save(obj, add=True)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/fields/files.py", line 287, in pre_save
    file.save(file.name, file.file, save=False)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/fields/files.py", line 86, in save
    name = self.field.generate_filename(self.instance, name)
  File "/usr/local/lib/python3.5/dist-packages/django/db/models/fields/files.py", line 306, in generate_filename
    return self.storage.generate_filename(filename)
  File "/usr/local/lib/python3.5/dist-packages/django/core/files/storage.py", line 97, in generate_filename
    dirname, filename = os.path.split(filename)
  File "/usr/lib/python3.5/posixpath.py", line 103, in split
    i = p.rfind(sep) + 1
AttributeError: 'NoneType' object has no attribute 'rfind'

Answer 1

Your user_directory_path function doesn't return anything (or, more exactly, it's dioesn't explicitely return anything so it implicitely returns None ). It has to return the full file path (relative to your settings.MEDIA_ROOT ) including the filename:

upload_to may also be a callable, such as a function. This will be called to obtain the upload path, including the filename. This callable must accept two arguments and return a Unix-style path (with forward slashes) to be passed along to the storage system

https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.FileField.upload_to