if (
        single_not_embedded_field
        and lenient_issubclass(first_field.type_, BaseModel)
        and isinstance(received_body, FormData)
    ):
        fields_to_extract = get_cached_model_fields(first_field.type_)

    if isinstance(received_body, FormData):
        body_to_process = await _extract_form_body(fields_to_extract, received_body)

    if single_not_embedded_field: