public MarketOrder CreateMarketOrder(decimal filledPrice, decimal fee, decimal size, DateTime date, bool buy,
int portfolioEntryId)
{
// create a MarketOrder instance
var order = new MarketOrder(filledPrice, fee, size, date, buy, PortfolioEntryId: portfolioEntryId);
// add it to the repository
var id = _marketOrderRepository.Add(order);
// return the created instance with the ID generated by the repository
return(order with {
Id = id
});
}