我正在使用 asp.net MVC，試圖制作一個表格來顯示品牌在幾天內每天的總利潤，并且我正在努力解決如何包含品牌凈利潤為 0 的日子。在我查詢商店在給定時間范圍內的購買總數后，在名為purchaseQuery的變量中，它為我提供了品牌名稱、購買日期（作為整數）、該商品的價格以及該商品的數量在那次交易中購買的。假設每個品牌只銷售一種產品，并且該產品的價格每天都會波動。該代碼位于該查詢之后。purchasedItems = new List<BrandsTransactionItem>();foreach (var query in purchaseQuery){BrandsTransactionItem tempItem;tempItem = purchasedItems.Where(e => e.day == query.day).Where(e => e.brandName == query.brandName).FirstOrDefault();//If item not in list already, if (tempItem == null){ purchasedItems.Add(new BrandsTransactionItem() { brandName = query.brandName, day = query.day, totalPurchased = query.TotalPurchased, costOfItem = query.costOfItem });}// if it already exists, just add to amount purchasedelse{ tempItem.totalPurchased += query.totalPurchased;}}foreach (var item in purchasedItems){ double dailyProfit = (double)(item.totalPurchased * item.costOfItem); dailyProfit = Math.Round(dailyProfit, 2); // make it decimal of 2 // Items is the list that I want to display in MVC Items.Add(new BrandsProfit(){ brandName = item.brandName, day = item.day, totalDailyProfit = dailyProfit });}我想要進行轉換，以便 BrandsProfit 具有名稱、日期列表以及與每一天相對應的每日利潤列表。這樣，商品列表中的每個商品都將具有唯一的品牌名稱，因為它將適用于每次購買，而不是僅適用于購買該品牌商品的日期。我覺得我把事情變得過于復雜了，我主要擔心的是，如果一個品牌一天有 0 次購買，我可能會得到一個大小為 5 的天數列表，以及一個大小為 的購買列表4、我需要它們的尺寸相同。感謝您的幫助，并感謝您花時間閱讀我的問題。
1 回答
絕地無雙
TA貢獻1946條經驗 獲得超4個贊
此類問題非常適合使用 LINQ。
下面的 LINQ 查詢首先創建不同日期和品牌名稱的外連接。這為我們提供了全天可以加入的所有品牌的列表。這樣，每個品牌都會有相同的天數，即使它在某一天從未售出任何商品。
然后，它會根據該品牌/日期列表加入購買，如果當天沒有記錄該品牌的購買，則會使用 來創建零成本/數量的替代購買DefaultIfEmpty。
然后，該連接的結果將被投影到對象列表中BrandsProfit。
例如，如果某一天沒有購買某個品牌，您會注意到在示例數據列表中，“2”天的品牌“B”被注釋掉了；但在結果中，“2”天仍然存在品牌“B”的行，每日總利潤為零。
void Main()
{
var purchases = new List<Purchase>() {
new Purchase() { BrandName = "A", CostOfItem = 1.13M, Day = 1, TotalPurchased = 125 },
new Purchase() { BrandName = "B", CostOfItem = 1.52M, Day = 1, TotalPurchased = 165 },
new Purchase() { BrandName = "C", CostOfItem = 1.90M, Day = 1, TotalPurchased = 836 },
new Purchase() { BrandName = "A", CostOfItem = 1.74M, Day = 2, TotalPurchased = 583 },
//new Purchase() { BrandName = "B", CostOfItem = 1.52M, Day = 2, TotalPurchased = 785 },
new Purchase() { BrandName = "C", CostOfItem = 1.42M, Day = 2, TotalPurchased = 369 },
new Purchase() { BrandName = "A", CostOfItem = 1.93M, Day = 3, TotalPurchased = 789 },
new Purchase() { BrandName = "B", CostOfItem = 1.87M, Day = 3, TotalPurchased = 739 },
new Purchase() { BrandName = "C", CostOfItem = 1.78M, Day = 3, TotalPurchased = 436 },
};
var results = from day in purchases.Select(x => x.Day).Distinct()
from brand in purchases.Select(x => x.BrandName).Distinct()
join purchase in purchases on new { Brand = brand, Day = day } equals new { Brand = purchase.BrandName, Day = purchase.Day } into j
from result in j.DefaultIfEmpty(new Purchase() { BrandName = brand, Day = day, TotalPurchased = 0, CostOfItem = 0 })
select new BrandsProfit()
{
BrandName = result.BrandName,
Day = result.Day,
TotalDailyProfit = result.TotalPurchased * result.CostOfItem
};
Debug.WriteLine(JsonConvert.SerializeObject(results, Newtonsoft.Json.Formatting.Indented));
}
class Purchase
{
public string BrandName { get; set; }
public int Day { get; set; }
public int TotalPurchased { get; set; }
public decimal CostOfItem { get; set; }
}
class BrandsProfit
{
public string BrandName { get; set; }
public int Day { get; set; }
public decimal TotalDailyProfit { get; set; }
}
產生以下結果：-
[
{
"BrandName": "A",
"Day": 1,
"TotalDailyProfit": 141.25
},
{
"BrandName": "B",
"Day": 1,
"TotalDailyProfit": 250.80
},
{
"BrandName": "C",
"Day": 1,
"TotalDailyProfit": 1588.40
},
{
"BrandName": "A",
"Day": 2,
"TotalDailyProfit": 1014.42
},
{
"BrandName": "B",
"Day": 2,
"TotalDailyProfit": 0.0
},
{
"BrandName": "C",
"Day": 2,
"TotalDailyProfit": 523.98
},
{
"BrandName": "A",
"Day": 3,
"TotalDailyProfit": 1522.77
},
{
"BrandName": "B",
"Day": 3,
"TotalDailyProfit": 1381.93
},
{
"BrandName": "C",
"Day": 3,
"TotalDailyProfit": 776.08
}
]
如果您不想繼續使用上面的示例，您可以考慮更新用于生成數據的源查詢，以purchaseQuery使用像上面這樣的外連接...這樣您就會有一個行代表品牌/天的每個組合，即使某個品牌從未在特定日期銷售過。
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