type_utils

trestle.common.type_utils

Utilities for dealing with models.

Attributes

logger = logging.getLogger(__name__) module-attribute

Functions

get_inner_type(collection_field_type)

Get the inner model in a generic collection model such as a List or a Dict.

For a dict the return type is of the value and not the key.

Parameters:

Name	Type	Description	Default
collection_field_type	Union[Type[List[Any]], Type[Dict[str, Any]]]	Provided type annotation from a pydantic object	required

Returns:

Type	Description
Type[Any]	The desired type.

Source code in trestle/common/type_utils.py

def get_inner_type(collection_field_type: Union[Type[List[Any]], Type[Dict[str, Any]]]) -> Type[Any]:
    """Get the inner model in a generic collection model such as a List or a Dict.

    For a dict the return type is of the value and not the key.

    Args:
        collection_field_type: Provided type annotation from a pydantic object

    Returns:
        The desired type.
    """
    try:
        # Pydantic special cases must be dealt with here:
        _, _, singular_type = _get_model_field_info(collection_field_type)
        if singular_type is not None:
            return singular_type
        return typing_extensions.get_args(collection_field_type)[-1]
    except Exception as e:
        logger.debug(e)
        raise err.TrestleError('Model type is not a Dict or List') from e

get_origin(field_type)

Generalized and robust get_origin function.

This function is derived from work by pydantic, however, avoids complications from various python versions.

Source code in trestle/common/type_utils.py

def get_origin(field_type: Type[Any]) -> Optional[Type[Any]]:
    """Generalized and robust get_origin function.

    This function is derived from work by pydantic, however, avoids complications
    from various python versions.
    """
    # This executes a fallback that allows a list to be generated from a constrained list.
    return typing_extensions.get_origin(field_type) or getattr(field_type, '__origin__', None)

is_collection_field_type(field_type)

Check whether a type hint is a collection type as used by OSCAL.

Specifically this is whether the type is a list or not.

Parameters:

Name	Type	Description	Default
field_type	Type[Any]	A type or a type alias of a field typically as served via pydantic introspection	required

Returns:

Type	Description
bool	True if it is a collection type list.

Source code in trestle/common/type_utils.py

def is_collection_field_type(field_type: Type[Any]) -> bool:
    """Check whether a type hint is a collection type as used by OSCAL.

    Specifically this is whether the type is a list or not.

    Args:
        field_type: A type or a type alias of a field typically as served via pydantic introspection

    Returns:
        True if it is a collection type list.
    """
    # first check if it is a pydantic __root__ object
    _, root_type, _ = _get_model_field_info(field_type)
    if root_type == 'List':
        return True
    # Retrieves type from a type annotation
    origin_type = get_origin(field_type)
    return origin_type == list

handler: python