如何使用Linq在C＃中創建if else語句

Question

我正在用linq創建一個web api到sql。 我需要在我的內容中添加一個if語句。 我無法在網上找到任何東西似乎每個人都在使用entityframework。

public List<customerorderhistory> GetCustomerOrderHistory(string customerID)
{
    try 
    {
        List<customerorderhistory> results = new List<customerorderhistory>();
        NorthwindDataContext dc = new NorthwindDataContext();
        foreach (CustOrderHistResult oneOrder in dc.CustOrderHist(customerID))
        {
            results.Add(new CustomerOrderHistory()
            {
                ProductName = oneOrder.ProductName,
                Total = oneOrder.Total ?? 0
            });
        }
        return results;
    }
    catch (Exception ex)
    {
        //  Return any exception messages back to the Response header
        OutgoingWebResponseContext response = WebOperationContext.Current.OutgoingResponse;
        response.StatusCode = System.Net.HttpStatusCode.InternalServerError;
        response.StatusDescription = ex.Message.Replace("\r\n", "");
        return null;
    }
}

他就是我所嘗試過的。 我想我可能會把if語句放在錯誤的地方。 任何幫助，將不勝感激。

public List<customerorderhistory> GetCustomerOrderHistory(string customerID)
{
    try 
    {
        List<customerorderhistory> results = new List<customerorderhistory>();
        NorthwindDataContext dc = new NorthwindDataContext();
        foreach (CustOrderHistResult oneOrder in dc.CustOrderHist(customerID))
        {
            results.Add(new CustomerOrderHistory()
            {
                if (oneOrder.RecordID == 'A')
                {
                    ProductName = "Archived Product"
                }
                else
                {
                ProductName = oneOrder.ProductName,
                }
                Total = oneOrder.Total ?? 0
            });
        }
        return results;
    }
    catch (Exception ex)
    {
        //  Return any exception messages back to the Response header
        OutgoingWebResponseContext response = WebOperationContext.Current.OutgoingResponse;
        response.StatusCode = System.Net.HttpStatusCode.InternalServerError;
        response.StatusDescription = ex.Message.Replace("\r\n", "");
        return null;
    }
}

Answer 1

假設你想掩蓋產品名稱，如果oneOrder.ProductID == 'A' ......

results.Add(new CustomerOrderHistory
{
    /*...*/,
    ProductName = (oneOrder.RecordID == 'A' ? "Archived Product" : oneOrder.ProductName),
    /*... */
});

使用條件運算符分配時可以放置條件 。

（可選）您可以在實例化對象之前將其存儲在變量中：

var productName = oneOrder.ProductName;
if (oneOrder.ProductID == 'A')
{
    productName = "Archived Product";
}
results.Add(new CustomerOrderHistory
{
    /*...*/,
    ProductName = productName,
    /*... */
});