{"record":{"id":"031fe3bdd60e3a53","repo":"reflex-dev/reflex","slug":"missing-value-for-environment-variable-field-name","errorCode":null,"errorMessage":"Missing value for environment variable {field.name} and no default value found","messagePattern":"Missing value for environment variable (.+?) and no default value found","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"packages/reflex-base/src/reflex_base/environment.py","lineNumber":51,"sourceCode":"\ndef get_default_value_for_field(field: dataclasses.Field) -> Any:\n    \"\"\"Get the default value for a field.\n\n    Args:\n        field: The field.\n\n    Returns:\n        The default value.\n\n    Raises:\n        ValueError: If no default value is found.\n    \"\"\"\n    if field.default != dataclasses.MISSING:\n        return field.default\n    if field.default_factory != dataclasses.MISSING:\n        return field.default_factory()\n    msg = f\"Missing value for environment variable {field.name} and no default value found\"\n    raise ValueError(msg)\n\n\n# TODO: Change all interpret_.* signatures to value: str, field: dataclasses.Field once we migrate rx.Config to dataclasses\ndef interpret_boolean_env(value: str, field_name: str) -> bool:\n    \"\"\"Interpret a boolean environment variable value.\n\n    Args:\n        value: The environment variable value.\n        field_name: The field name.\n\n    Returns:\n        The interpreted value.\n\n    Raises:\n        EnvironmentVarValueError: If the value is invalid.\n    \"\"\"\n    true_values = [\"true\", \"1\", \"yes\", \"y\"]\n    false_values = [\"false\", \"0\", \"no\", \"n\"]","sourceCodeStart":33,"sourceCodeEnd":69,"githubUrl":"https://github.com/reflex-dev/reflex/blob/45b8ed5ab735f8a56bbb09a42384f030eb0208e7/packages/reflex-base/src/reflex_base/environment.py#L33-L69","documentation":"Thrown when building a dataclass-driven config/state from environment variables and a required field has neither an environment value nor a declared default or default_factory. The fallback lookup in get_default_value_for_field finds dataclasses.MISSING for both, so it raises ValueError naming the field.","triggerScenarios":"A dataclass field without a default whose environment variable is unset, passed to the env-parsing machinery (e.g. update_from_env / get_default_value_for_field on fields like a required API key).","commonSituations":"Deploying without setting required env vars (DATABASE_URL, API keys), renaming env vars between versions, or missing .env files in CI/production.","solutions":["Set the missing environment variable named in the message (export it or add it to .env)","Give the dataclass field a default or default_factory if it's optional","Add a startup check listing required env vars before the app boots"],"exampleFix":"# before\n@dataclasses.dataclass\nclass Settings:\n    api_key: str  # no default\n# shell: API_KEY unset -> ValueError\n# after (option 1)\nexport API_KEY=...\n# after (option 2)\n@dataclasses.dataclass\nclass Settings:\n    api_key: str = \"\"\n","handlingStrategy":"validation","validationCode":"import os\nrequired = [f.name for f in dataclasses.fields(Settings)\n            if f.default is dataclasses.MISSING and f.default_factory is dataclasses.MISSING]\nmissing = [n for n in required if os.environ.get(n) is None]\nif missing:\n    raise SystemExit(f\"Missing env vars: {missing}\")","typeGuard":"null","tryCatchPattern":"try:\n    Settings.from_env()\nexcept ValueError as e:\n    if \"Missing value for environment variable\" in str(e):\n        # prompt or apply defaults\n        ...","preventionTips":["Fail fast at boot with an env checklist","Use .env files locally and a secrets manager in prod; never rely on memory for required vars"],"tags":["environment","config","missing-value","dataclass"],"backgroundTag":"missing-env-var","analyzedSha":"45b8ed5ab735f8a56bbb09a42384f030eb0208e7","analyzedAt":"2026-08-28T19:25:27.644Z","schemaVersion":2},"datasetVersion":"2026-08-28T21:17:43.275Z"}