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Frequently Asked Questions

How can I compare output results between versions

See the --include-header config.

Why are elements out of order?

See the --compound-fields config.

Why do I get a TypeError: requires a single type

TypeError: typing.Optional requires a single type. Got Field(name=None,type=None,default=<dataclasses._MISSING_TYPE object at 0x7f79f4b0d700>,default_facto.

This error means the typing annotations for a model are ambiguous because they collide with a class field. In order to resolve this issue you have to enable the --postponed-annotations config.

Why non-nullable fields are marked as optional?

A TypeError is raised if a dataclasses field without a default value follows a field with a default value. If you are using >= Python 3.10 you can enable the kwOnly option in the format config.

If you can't update just yet please check the attrs plugin!