FileField with UUID filename

[Jon Ribbens]

I have a model which basically just represents a file. I want to use a UUID as the filename. I could do the following:

    def _get_filename(instance, filename):
        return str(uuid.uuid4())

    class File(Model):
       content = FileField(db_index=True, upload_to=_get_filename)
       filetype = CharField("MIME Type", max_length=256)

which does work however it is sub-optimal in a couple of ways:

• the UUID is stored as a VARCHAR in the database
• the UUID is not used as the primary key
• there is a pointless additional integer field as the primary key
• you can't even add unique=True to the field

So I was wondering:

• why does FileField refuse to allow its use in a unique index or as the primary key?
• how can I get FileField to use a UUID field in the database?

Any thoughts would be greatly appreciated.

[Tim Graham]

See https://code.djangoproject.com/ticket/4345 for the ticket that disallowed primary_key/unique on FileField.

You can write a custom field to get FileField to use a UUID in the database (and likely also lift the other restrictions you want to bypass).

[Jon Ribbens]

On Tuesday, 6 September 2016 17:05:39 UTC+1, Tim Graham wrote:

See https://code.djangoproject.com/ticket/4345 for the ticket that disallowed primary_key/unique on FileField.

I've now opened a new ticket #27188 to suggest reversing this change ;-)

 

You can write a custom field to get FileField to use a UUID in the database (and likely also lift the other restrictions you want to bypass).

Yes, I was wondering how to do that because it's not at all obvious. However I have since decided that I simply need a custom Storage class like this:

class ChecksumStorage(FileSystemStorage):
    """Store files in the file system with filename based on file contents."""
    def save(self, name, content, max_length=None):
        checksum = hashlib.sha256()
        for data in content.chunks():
            checksum.update(data)
        return super().save(checksum.hexdigest(), content)

and then I don't need a model at all, I can just refer to the files with a CharField(max_length=64).