无法在自定义存储中读取Django FieldFile`

Question

I'm attempting to make a custom file storage class for my Django app that transparently logs a hash of all files saved.

My test storage class is pretty trivial:

from django.core.files.storage import Storage
from django.db.models.fields.files import FieldFile

from utils import get_text_hash

class MyStorage(Storage)

    def _save(self, name, content):
        if isinstance(content, FieldFile):
            raw_content = content.open().read()
        else:
            raw_content = content
        assert isinstance(raw_content, basestring)
        print(get_text_hash(raw_content))
        return super(MyStorage, self)._save(name, content)

However, when I try and save a file in my app, I get the error:

'NoneType' object has no attribute 'read'

with the traceback ending on the line:

raw_content = content.open().read()

Why is open() returning None instead of a file handle? What's the proper way to access your raw file content inside a Django storage class?

Answer 1

raw_content = content.open().read()

change to

raw_content = content.read()

I think you can check these manuals.

Django Manual _save

_save(name, content)¶ Called by Storage.save(). The name will already have gone through get_valid_name() and get_available_name(), and the content will be a File object itself.

So content is File object.

Django Manual FieldFile.open

Opens or reopens the file associated with this instance in the specified mode. Unlike the standard Python open() method, it doesn't return a file descriptor.