{instance.uuid:x}{ext} raises an error

[amureki]

Greetings there, many thanks for the package! 👍

I have a usecase that is currently not supported:

class Item(models.Model):
    uid = models.UUIDField(
        default=uuid.uuid4,
        unique=True,
    ) # 3d678d69-44f1-4015-93fa-e3426eaca4fe
    image = models.ImageField(
        upload_to=FilePattern(
            filename_pattern=(
                "{instance.uuid:x}{ext}"
            ),
        ),
    )
    # image should be stored as hex version of a given uuid
    #  3d678d6944f1401593fae3426eaca4fe.jpg 

I could imagine extending SlugFormatter (and also renaming it to fit an extended purpose) to support uuid type.
Here is a dirty example to give an idea:

class SlugFormatter(Formatter):
    format_spec_pattern = re.compile(r"(\.\d+)?([\d\w]+)?")

    def format_field(self, value, format_spec):
        precision, ftype = self.format_spec_pattern.match(format_spec).groups()
        if precision:
            precision = int(precision.lstrip("."))
        if ftype == "slug":
            return slugify(value, allow_unicode=False)[:precision]
        if ftype == "uuid":
            return value.hex[:precision]
        return super().format_field(value=value, format_spec=format_spec)

But I am not sure if you'd be willing to go this direction.
Happy to hear your opinion here!

Best,
Rust

[codingjoe]

Hi there,

Sadly, Python's UUID implementation doesn't support more comprehensive __format__ options.
This package implements its own UUID version, could cast UUIDs in the formatter.
However, you probably shouldn't use the type descriptor. As that once should describe the output, not the input type.

You are welcome to open a PR with a suggestion.
Cheers!
Joe