Back to Basic: Fundamental Data Structure in C#

ProcessTransactionWithOnlyList.cs

public static void ProcessTransactionWithOnlyList(IList<TransactionDTO> pTransactions, IList<PortfolioDTO> pPortfolios, IList<PortPriceSouceDTO> pPortPriceSources)
{
    // Iterate through transactions and find corresponding portfolio
    foreach (var transaction in pTransactions)
    {
        // Use LINQ to find the portfolio with the matching PortfolioId
        var portfolio = pPortfolios.FirstOrDefault(p => p.PortfolioId == transaction.PortfolioId);
        if (portfolio != null)
        {
            // You can save or process the transaction with the portfolio here
            //....
        }

        var portPriceSource = pPortPriceSources.FirstOrDefault(p => p.PortfolioId == transaction.PortfolioId);
        if (portPriceSource != null)
        {
            // You can save or process the transaction with the portfolio here
            //....
        }
    }
}