{"record":{"id":"231b15722fdd4be9","repo":"reflex-dev/reflex","slug":"cannot-determine-the-source-code-for-the-var-in-s","errorCode":null,"errorMessage":"Cannot determine the source code for the var in {self.func!r}.","messagePattern":"Cannot determine the source code for the var in (.+?)\\.","errorType":"exception","errorClass":"VarValueError","httpStatus":null,"severity":"error","filePath":"packages/reflex-base/src/reflex_base/vars/dep_tracking.py","lineNumber":338,"sourceCode":"            self.load_attr_or_method(instruction)\n\n    def _eval_var(self, positions: dis.Positions) -> Var:\n        \"\"\"Evaluate instructions from the wrapped function to get the Var object.\n\n        Args:\n            positions: The disassembly positions of the get_var_value call.\n\n        Returns:\n            The Var object.\n\n        Raises:\n            VarValueError: if the source code for the var cannot be determined.\n        \"\"\"\n        # Get the original source code and eval it to get the Var.\n        module = inspect.getmodule(self.func)\n        if module is None or self._get_var_value_positions is None:\n            msg = f\"Cannot determine the source code for the var in {self.func!r}.\"\n            raise VarValueError(msg)\n        start_line = self._get_var_value_positions.end_lineno\n        start_column = self._get_var_value_positions.end_col_offset\n        end_line = positions.end_lineno\n        end_column = positions.end_col_offset\n        if (\n            start_line is None\n            or start_column is None\n            or end_line is None\n            or end_column is None\n        ):\n            msg = f\"Cannot determine the source code for the var in {self.func!r}.\"\n            raise VarValueError(msg)\n        source = inspect.getsource(module).splitlines(True)[start_line - 1 : end_line]\n        # Create a python source string snippet.\n        if len(source) > 1:\n            snipped_source = \"\".join([\n                *source[0][start_column:],\n                *source[1:-1],","sourceCodeStart":320,"sourceCodeEnd":356,"githubUrl":"https://github.com/reflex-dev/reflex/blob/45b8ed5ab735f8a56bbb09a42384f030eb0208e7/packages/reflex-base/src/reflex_base/vars/dep_tracking.py#L320-L356","documentation":"To track dependencies of a cached var, Reflex re-evaluates the var expression from the function's original source (via inspect). If inspect.getmodule(self.func) returns None or the recorded source positions are missing, Reflex cannot reconstruct the expression and raises VarValueError.","triggerScenarios":"A cached var function whose module cannot be determined by inspect, or whose return-expression bytecode positions are absent. Typical with functions defined in exec()/eval(), the REPL, Jupyter notebooks (sometimes), or objects wrapped so that __module__/code filename metadata is lost.","commonSituations":"Prototyping state in a notebook or REPL; building apps from strings with exec; functools.partial or custom decorators that hide the original function's module; frozen/compiled environments where source files are not on disk.","solutions":["Move the state/cached var definition into a real .py module file and import it normally.","Remove decorators/wrappers (like functools.wraps-less wrappers) that strip __module__ or __code__ metadata from the cached var function.","Ensure the source file is present and readable at runtime (not stripped in deployment)."],"exampleFix":"# before (REPL / exec'd string)\napp_code = \"class S(rx.State):\\n  @rx.var(cached=True)\\n  def v(self) -> int: return self.x\"\nexec(app_code)\n\n# after\n# state.py\nclass S(rx.State):\n    @rx.var(cached=True)\n    def v(self) -> int:\n        return self.x","handlingStrategy":"validation","validationCode":"import inspect\n\ndef inspectable(func) -> bool:\n    return inspect.getmodule(func) is not None and inspect.getsourcefile(func) is not None","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Define state and cached vars in real .py files, not exec/REPL/notebook strings.","Avoid wrappers that strip __module__/__code__ metadata from cached var functions.","Keep source files shipped with deployments."],"tags":["reflex","cached-var","inspect","source-introspection"],"backgroundTag":"function-source-introspection-failed","analyzedSha":"45b8ed5ab735f8a56bbb09a42384f030eb0208e7","analyzedAt":"2026-08-28T19:25:27.644Z","schemaVersion":2},"datasetVersion":"2026-08-28T21:17:43.275Z"}