{"record":{"id":"7c5d99a96e641479","repo":"pola-rs/polars","slug":"enum-categories-must-be-strings-enum-type-name","errorCode":null,"errorMessage":"Enum categories must be strings; `{enum_type_name}` values are integers","messagePattern":"Enum categories must be strings; `(.+?)` values are integers","errorType":"exception","errorClass":"TypeError","httpStatus":null,"severity":"error","filePath":"py-polars/src/polars/datatypes/classes.py","lineNumber":1046,"sourceCode":"    >>> pl.Enum([\"north\", \"south\", \"east\", \"west\"])\n    Enum(categories=['north', 'south', 'east', 'west'])\n\n    Initialise from an existing Python enumeration:\n\n    >>> from http import HTTPMethod\n    >>> pl.Enum(HTTPMethod)\n    Enum(categories=['CONNECT', 'DELETE', 'GET', 'HEAD', 'OPTIONS', 'PATCH', 'POST', 'PUT', 'TRACE'])\n    \"\"\"  # noqa: W505\n\n    categories: Series\n\n    def __init__(self, categories: Series | Iterable[str] | type[enum.Enum]) -> None:\n        if isclass(categories) and issubclass(categories, enum.Enum):\n            for enum_subclass in (enum.Flag, enum.IntEnum):\n                if issubclass(categories, enum_subclass):\n                    enum_type_name = categories.__name__\n                    msg = f\"Enum categories must be strings; `{enum_type_name}` values are integers\"\n                    raise TypeError(msg)\n\n            enum_values = [\n                getattr(v, \"value\", v) for v in categories.__members__.values()\n            ]\n            categories = pl.Series(values=enum_values)\n        elif not isinstance(categories, pl.Series):\n            categories = pl.Series(values=categories)\n\n        if categories.is_empty():\n            self.categories = pl.Series(name=\"category\", dtype=String)\n            return\n\n        if categories.has_nulls():\n            msg = \"Enum categories must not contain null values\"\n            raise TypeError(msg)\n\n        if (dtype := categories.dtype) != String:\n            msg = f\"Enum categories must be strings; found data of type {dtype}\"","sourceCodeStart":1028,"sourceCodeEnd":1064,"githubUrl":"https://github.com/pola-rs/polars/blob/df599052daf96e7a9cc30a3b0c6bd25d6947e3c0/py-polars/src/polars/datatypes/classes.py#L1028-L1064","documentation":"Error \"Enum categories must be strings; `{enum_type_name}` values are integers\" thrown in pola-rs/polars.","triggerScenarios":"Thrown at py-polars/src/polars/datatypes/classes.py:1046 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"df599052daf96e7a9cc30a3b0c6bd25d6947e3c0","analyzedAt":"2026-08-16T12:10:03.978Z","schemaVersion":2},"datasetVersion":"2026-08-16T13:17:31.715Z"}