{"record":{"id":"200785be2fef9d08","repo":"reflex-dev/reflex","slug":"the-var-is-string-argument-is-not-supported-for-v","errorCode":null,"errorMessage":"The _var_is_string argument is not supported for Var.","messagePattern":"The _var_is_string argument is not supported for Var\\.","errorType":"exception","errorClass":"TypeError","httpStatus":null,"severity":"error","filePath":"packages/reflex-base/src/reflex_base/vars/base.py","lineNumber":791,"sourceCode":"\n        Args:\n            _var_type: The new type of the Var.\n            merge_var_data: VarData to merge into the existing VarData.\n            **kwargs: Var fields to update.\n\n        Returns:\n            A new Var with the updated fields overwriting the corresponding fields in this Var.\n\n        Raises:\n            TypeError: If _var_is_local, _var_is_string, or _var_full_name_needs_state_prefix is not None.\n        \"\"\"\n        if kwargs.get(\"_var_is_local\", False) is not False:\n            msg = \"The _var_is_local argument is not supported for Var.\"\n            raise TypeError(msg)\n\n        if kwargs.get(\"_var_is_string\", False) is not False:\n            msg = \"The _var_is_string argument is not supported for Var.\"\n            raise TypeError(msg)\n\n        if kwargs.get(\"_var_full_name_needs_state_prefix\", False) is not False:\n            msg = \"The _var_full_name_needs_state_prefix argument is not supported for Var.\"\n            raise TypeError(msg)\n        value_with_replaced = dataclasses.replace(\n            self,\n            _var_type=_var_type or self._var_type,\n            _var_data=VarData.merge(\n                kwargs.get(\"_var_data\", self._var_data), merge_var_data\n            ),\n            **kwargs,\n        )\n\n        if (js_expr := kwargs.get(\"_js_expr\")) is not None:\n            object.__setattr__(value_with_replaced, \"_js_expr\", js_expr)\n\n        return value_with_replaced\n","sourceCodeStart":773,"sourceCodeEnd":809,"githubUrl":"https://github.com/reflex-dev/reflex/blob/45b8ed5ab735f8a56bbb09a42384f030eb0208e7/packages/reflex-base/src/reflex_base/vars/base.py#L773-L809","documentation":"Var._replace rejects the legacy keyword _var_is_string. String formatting state now lives in VarData (formatting/transform hooks), so passing the old boolean raises TypeError. Companion guards reject _var_is_local and _var_full_name_needs_state_prefix.","triggerScenarios":"Calling var._replace(_var_is_string=True); code or libraries written for an older reflex Var that accepted these flags; copy-pasted internal Reflex source after upgrading.","commonSituations":"Reflex version upgrades where Var was refactored (flags moved to VarData); stale component libraries; migration of large codebases using private Var APIs.","solutions":["Drop the kwarg and express string-ness via the public API, e.g. Var.create(value, string=False) at creation time or VarData formatting hooks","Update to the current _replace signature","Upgrade pinned third-party reflex packages","Grep for _var_is_string across the project and migrate all uses"],"exampleFix":"# before\nv = v._replace(_var_is_string=True)\n# after\nv = Var.create(v, string=True)  # set string-ness at creation","handlingStrategy":"type-guard","validationCode":"kwargs.pop('_var_is_string', None)\nv = v._replace(**kwargs)","typeGuard":"def is_supported_replace_kwarg(name: str) -> bool:\n    return name not in {'_var_is_local', '_var_is_string', '_var_full_name_needs_state_prefix'}","tryCatchPattern":null,"preventionTips":["Set string-ness at creation via Var.create(value, string=...)","Pin or update third-party reflex libs together with reflex itself"],"tags":["reflex","var","deprecated-argument","upgrade"],"backgroundTag":"removed-api-argument","analyzedSha":"45b8ed5ab735f8a56bbb09a42384f030eb0208e7","analyzedAt":"2026-08-28T19:25:27.644Z","schemaVersion":2},"datasetVersion":"2026-08-28T21:17:43.275Z"}