Blob.upload_from_file doesn't work for file-like objects without size parameter

[theacodes]

When using StringIO, io.BytesIO or other file-like objects (such as Flask/werkzeug's file upload object), trying to upload via Blob.upload_from_file doesn't work because it attempts to find the size of the object using os.stat throwing a AttributeError: StringIO instance has no attribute 'fileno'. Passing in the size manually fixes this, but imo this inconsistency shouldn't burden the user as there are other ways than fileno to determine the size of a StringIO or io.BytesIO instance (seek, tell).

At any rate, the error message could be more helpful.

[dhermes]

Can you give a stacktrace of the error message?

The offending line is

        # Get the basic stats about the file.
        total_bytes = size or os.fstat(file_obj.fileno()).st_size

which as @jonparrott points out, assumes the file-like object is a file (from the stdlib).

[theacodes]

Traceback (most recent call last):
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/jonwayne/workspace/getting-started-python/env/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/jonwayne/workspace/getting-started-python/oauth2/__init__.py", line 33, in decr
    return f(*args, **kwargs)
  File "/Users/jonwayne/workspace/getting-started-python/bookshelf/crud.py", line 57, in add
    image_url = upload_image_file(request.files.get('image'))
  File "/Users/jonwayne/workspace/getting-started-python/bookshelf/crud.py", line 25, in upload_image_file
    current_app.config['ALLOWED_EXTENSIONS']
  File "/Users/jonwayne/workspace/getting-started-python/storage/__init__.py", line 52, in upload_file
    blob.upload_from_file(file)
  File "/Users/jonwayne/workspace/getting-started-python/env/src/gcloud/gcloud/storage/blob.py", line 395, in upload_from_file
    total_bytes = size or os.fstat(file_obj.fileno()).st_size
UnsupportedOperation: fileno

[dhermes]

Ha, ok. Doesn't provide anything we didn't know.

[theacodes]

Heh, let me know if there's anything else I can provide to help here. The file-like object is a flask file upload (werkzeug.FileStorage). It fails likewise when using blob.upload_from_file(file) and blob.upload_from_file(file.stream).