{"record":{"id":"3ded892d1ac6699c","repo":"pathwaycom/pathway","slug":"schema-must-be-specified-consider-using-pw-schem","errorCode":null,"errorMessage":"Schema must be specified. Consider using `pw.schema_from_csv` for generating schema from a CSV file","messagePattern":"Schema must be specified\\. Consider using `pw\\.schema_from_csv` for generating schema from a CSV file","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"python/pathway/io/_utils.py","lineNumber":250,"sourceCode":"    schema: type[Schema],\n) -> tuple[type[Schema], dict[str, Any]]:\n    value_fields = _form_value_fields(schema)\n    return schema, dict(\n        # There is a distinction between an empty set of columns denoting\n        # the primary key and None. If any (including empty) set of keys if provided,\n        # then it will be used to compute the primary key.\n        key_field_names=schema.primary_key_columns(),\n        value_fields=value_fields,\n    )\n\n\ndef assert_schema_not_none(\n    schema: type[Schema] | None,\n    data_format_type: str | None = None,\n) -> type[Schema]:\n    if schema is None:\n        if data_format_type == \"dsv\":\n            raise ValueError(\n                \"Schema must be specified. \"\n                \"Consider using `pw.schema_from_csv` for generating schema from a CSV file\"\n            )\n        else:\n            raise ValueError(\"Schema must be specified.\")\n    else:\n        return schema\n\n\nclass PlaintextKeySchema(pw.Schema):\n    key: str\n\n\nclass RawKeySchema(pw.Schema):\n    key: bytes\n\n\ndef construct_raw_data_schema_by_flags(","sourceCodeStart":232,"sourceCodeEnd":268,"githubUrl":"https://github.com/pathwaycom/pathway/blob/fa2f74a4649b7c5908690cf60137263d8d80de5f/python/pathway/io/_utils.py#L232-L268","documentation":"Error \"Schema must be specified. Consider using `pw.schema_from_csv` for generating schema from a CSV file\" thrown in pathwaycom/pathway.","triggerScenarios":"Thrown at python/pathway/io/_utils.py:250 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Provide the schema explicitly via the schema parameter, or generate it with pw.schema_from_csv for CSV input."],"exampleFix":"schema = pw.schema_from_csv('data.csv'); pw.io.csv.read('data.csv', schema=schema)","handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"fa2f74a4649b7c5908690cf60137263d8d80de5f","analyzedAt":"2026-08-15T01:48:17.006Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}