BoundaryML/baml · error · AttributeError

Value not found.

Error message

Value {name} not found.

What it means

NewEnumValues.__getattr__ lets you access enum values as attributes (e.g. bldr.values.RED). If the attribute name was never registered via add_value, it raises AttributeError('Value {name} not found.').

Solutions

1. Call add_value(name) before accessing bldr.values.<name>
2. Verify the exact value name spelling
3. Use list_values() to see registered names
4. Wrap access in try/except AttributeError

Example fix

// before
val = enum_b.values.REDD
// after
enum_b.add_value("RED")
val = enum_b.values.RED

known = {n for n, _ in enum_b.list_values()}
assert value_name in known, f"{value_name} not added yet"

def has_value(enum_b, name: str) -> bool:
    return name in {n for n, _ in enum_b.list_values()}

try:
    val = enum_b.values.RED
except AttributeError as e:
    if "Value" in str(e) and "not found" in str(e):
        val = enum_b.add_value("RED")
    else:
        raise

When it happens

Trigger: Attribute access on the values object for a name not passed to add_value; typos in value names; accessing values after constructing a new builder object that lost the tracking set.

Common situations: Typo in an enum value name; copy-pasted code referencing values from a different enum; accessing a value before calling add_value.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

• Class with name already exists.
• Enum with name already exists.
• Value already exists.
• attempted to read a property that has no defined type, this…
• attempted to read a property that has no defined type, this…

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/0200b3921c81f1c8. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_client_python/python_src/baml_py/type_builder.py:183

    def list_values(self) -> typing.List[typing.Tuple[str, EnumValueBuilder]]:
        return [(name, self.__bldr.value(name)) for name in self.__values]

    def add_value(self, name: str) -> "EnumValueBuilder":
        if name in self.__values:
            raise ValueError(f"Value {name} already exists.")
        self.__values.add(name)
        # NOTE(sam): why is this inconsistent between classes and enums?
        return self.__bldr.value(name)


class NewEnumValues:
    def __init__(self, enum_bldr: EnumBuilder, values: typing.Set[str]):
        self.__bldr = enum_bldr
        self.__values = values

    def __getattr__(self, name: str) -> "EnumValueBuilder":
        if name not in self.__values:
            raise AttributeError(f"Value {name} not found.")
        return self.__bldr.value(name)


class EnumValueViewer:
    def __init__(self, bldr: "EnumValueBuilder"):
        self.__bldr = bldr

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