{"record":{"id":"00d64b8f9a348cab","repo":"pathwaycom/pathway","slug":"table-with-schema-argument-has-to-have-the-same","errorCode":null,"errorMessage":"Table.with_schema() argument has to have the same column names as in the table.","messagePattern":"Table\\.with_schema\\(\\) argument has to have the same column names as in the table\\.","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"python/pathway/internals/table.py","lineNumber":2217,"sourceCode":"        for col in columns:\n            if isinstance(col, expr.ColumnReference):\n                new_columns.pop(col.name)\n            else:\n                assert isinstance(col, str)\n                new_columns.pop(col)\n        columns_wrapped = {\n            name: self._wrap_column_in_context(self._rowwise_context, column, name)\n            for name, column in new_columns.items()\n        }\n        return self._with_same_universe(*columns_wrapped.items())\n\n    @trace_user_frame\n    @contextualized_operator\n    @check_arg_types\n    def _with_schema(self, schema: type[Schema]) -> Table:\n        \"\"\"Returns updated table with a forced schema on it.\"\"\"\n        if schema.keys() != self.schema.keys():\n            raise ValueError(\n                \"Table.with_schema() argument has to have the same column names as in the table.\"\n            )\n        context = clmn.SetSchemaContext(\n            _id_column=self._id_column,\n            _new_properties={\n                self[name]._to_internal(): schema.column_properties(name)\n                for name in self.column_names()\n            },\n            _id_column_props=schema.__universe_properties__,\n        )\n        return self._table_with_context(context)\n\n    @trace_user_frame\n    @check_arg_types\n    def update_types(self, **kwargs: Any) -> Table:\n        \"\"\"Updates types in schema. Has no effect on the runtime.\"\"\"\n\n        for name in kwargs.keys():","sourceCodeStart":2199,"sourceCodeEnd":2235,"githubUrl":"https://github.com/pathwaycom/pathway/blob/fa2f74a4649b7c5908690cf60137263d8d80de5f/python/pathway/internals/table.py#L2199-L2235","documentation":"Raised by Table._with_schema() (backing with_schema) when the provided schema class's column-name set differs from the table's current column names. with_schema forces column properties (types, defaults) onto existing columns; it cannot add, remove, or reorder columns.","triggerScenarios":"t.with_schema(MySchema) where MySchema's fields are not exactly t.schema.keys(); e.g. MySchema misses a column or adds one, or column was renamed before with_schema.","commonSituations":"Schema class out of sync with the connector's output (connector version added/removed a field); applying a schema meant for a different table; renaming columns then applying the original schema.","solutions":["Align the schema class so its field names exactly match t.column_names()","Or adjust the table first: select/rename/with_columns so names match the schema","Regenerate the schema definition from the actual table if the source of truth drifted","Prefer building the table with the schema at ingestion time (input with schema=MySchema) instead of patching afterwards"],"exampleFix":"# before\nclass NewSchema(pw.Schema):\n    a: int\nt2 = t.with_schema(NewSchema)  # t also has column 'b' -> ValueError\n\n# after\nclass NewSchema(pw.Schema):\n    a: int\n    b: str\nt2 = t.with_schema(NewSchema)","handlingStrategy":"validation","validationCode":"def with_schema_safe(t, schema):\n    assert schema.keys() == t.schema.keys(), (\n        f'{set(schema.keys())} != {set(t.schema.keys())}'\n    )\n    return t.with_schema(schema)","typeGuard":null,"tryCatchPattern":"try:\n    t2 = t.with_schema(S)\nexcept ValueError as e:\n    if 'same column names' in str(e):\n        raise ValueError(f'{t.column_names()} vs {list(S.keys())}') from e","preventionTips":["Apply the schema at connector creation instead of patching later","Keep Schema classes in one module and lint them against connector output","Re-check schema classes after connector upgrades"],"tags":["pathway","schema","with-schema","columns"],"backgroundTag":null,"analyzedSha":"fa2f74a4649b7c5908690cf60137263d8d80de5f","analyzedAt":"2026-08-15T01:48:17.006Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}