From a service layer that uses a domain object (OrderLine) vs primitives

better.py

def allocate(orderid:str, sku: str, qty: int, repo: AbstractRepository, session) -> str:
    """
    Obtains a list of Batches from data layer, validates OrderLine,
    calls the allocate domain service, and commits to database.
    """
    batches = repo.list()
    if not is_valid_sku(sku, batches):
        raise InvalidSKU(f'Invalid SKU: {sku}')
    ref = model.allocate(orderid, sku, qty, batches)
    session.commit()
    return ref

good.py

def allocate(orderid:str, sku: str, qty: int, repo: AbstractRepository, session) -> str:
    """
    Obtains a list of Batches from data layer, validates OrderLine,
    calls the allocate domain service, and commits to database.
    """
    batches = repo.list()
    if not is_valid_sku(sku, batches):
        raise InvalidSKU(f'Invalid SKU: {sku}')
    line = model.OrderLine(orderid, sku, qty)
    ref = model.allocate(line, batches)
    session.commit()
    return ref

old.py

def allocate(line: model.OrderLine, repo: AbstractRepository, session) -> str:
    """
    Obtains a list of Batches from data layer, validates OrderLine,
    calls the allocate domain service, and commits to database.
    """
    batches = repo.list()
    if not is_valid_sku(line, batches):
        raise InvalidSKU(f'Invalid SKU: {line.sku}')
    ref = model.allocate(line, batches)
    session.commit()
    return ref