{"record":{"id":"328c9c404db65682","repo":"reflex-dev/reflex","slug":"annotation-of-the-computed-var-assigned-to-the-dat","errorCode":null,"errorMessage":"Annotation of the computed var assigned to the data field should be provided.","messagePattern":"Annotation of the computed var assigned to the data field should be provided\\.","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"packages/reflex-components-gridjs/src/reflex_components_gridjs/datatable.py","lineNumber":68,"sourceCode":"\n        Args:\n            *children: The children of the component.\n            **props: The props to pass to the component.\n\n        Returns:\n            The datatable component.\n\n        Raises:\n            ValueError: If a pandas dataframe is passed in and columns are also provided.\n        \"\"\"\n        data = props.get(\"data\")\n        columns = props.get(\"columns\")\n\n        # The annotation should be provided if data is a computed var. We need this to know how to\n        # render pandas dataframes.\n        if is_computed_var(data) and data._var_type == Any:\n            msg = \"Annotation of the computed var assigned to the data field should be provided.\"\n            raise ValueError(msg)\n\n        if (\n            columns is not None\n            and is_computed_var(columns)\n            and columns._var_type == Any\n        ):\n            msg = \"Annotation of the computed var assigned to the column field should be provided.\"\n            raise ValueError(msg)\n\n        # If data is a pandas dataframe and columns are provided throw an error.\n        if (\n            types.is_dataframe(type(data))\n            or (isinstance(data, Var) and types.is_dataframe(data._var_type))\n        ) and columns is not None:\n            msg = \"Cannot pass in both a pandas dataframe and columns to the data_table component.\"\n            raise ValueError(msg)\n\n        # If data is a list and columns are not provided, throw an error","sourceCodeStart":50,"sourceCodeEnd":86,"githubUrl":"https://github.com/reflex-dev/reflex/blob/45b8ed5ab735f8a56bbb09a42384f030eb0208e7/packages/reflex-components-gridjs/src/reflex_components_gridjs/datatable.py#L50-L86","documentation":"data_table needs the Python type of data to serialize pandas DataFrames correctly. If data is a computed var annotated as Any (no return annotation), Reflex cannot tell whether it is a DataFrame.","triggerScenarios":"@rx.var-def computed var without a return annotation passed to rx.data_table(data=...) — data._var_type is Any.","commonSituations":"Writing @rx.var def get_data(self): return self.df without an annotation, often after refactoring or in dynamically-typed codebases.","solutions":["Annotate the computed var: @rx.var def get_data(self) -> pd.DataFrame: ...","Or annotate as the concrete list type you return"],"exampleFix":"# before\n@rx.var\ndef table_data(self):\n    return self.df\n# after\n@rx.var\ndef table_data(self) -> pd.DataFrame:\n    return self.df","handlingStrategy":"type-guard","validationCode":"import inspect\nret = inspect.signature(get_data.fn if hasattr(get_data, 'fn') else get_data).return_annotation\nassert ret is not inspect.Signature.empty, 'annotate the computed var feeding data_table'","typeGuard":"def computed_var_is_annotated(v: Any) -> bool:\n    return not (is_computed_var(v) and v._var_type is Any)","tryCatchPattern":null,"preventionTips":["Always annotate @rx.var return types","Enable pyright/mypy strictness on state modules"],"tags":["reflex","gridjs","computed-var","type-annotation"],"backgroundTag":"missing-type-annotation","analyzedSha":"45b8ed5ab735f8a56bbb09a42384f030eb0208e7","analyzedAt":"2026-08-28T19:25:27.644Z","schemaVersion":2},"datasetVersion":"2026-08-28T21:17:43.275Z"}