LINQ到實體 - 舍入到最近的美元，最近的半美元，或完全不

Question

我需要根據標識圓FinalPrice以下幾種方式：

• 0 =根本沒有;
• 1 =最多下一元
• 2 =最多到下一個半美元預計舍入的

實施例：

• ID 0：133.15 => 133.15
• ID 1：133.15 => 134.00
• ID 2：133.15 => 133.50

public IQueryable<MyObj> GetPrices() 
    { 
     int roundingId = 0; //0 = no rounding. 1 = dollar rounding. 2 = half-dollar rounding. 

     var prices = from ps in ObjectContext.Products 
     select new MyObj 
     { 
      FinalPrice = (ps.IsCustomPrice ? ps.CustomPrice : ps.Retail), 
     } 

     return prices; 
    } 

我希望能使用自定義函數，以在LINQ to Entities中做這個取整操作...

Answer 1

這將爲你工作。你可以清理供自己使用，但基本上你只是使用%模運算符來獲得美分和? :三元運算符來選擇正確的值

var prices = from ps in ObjectContext.Products 
      let cents = ps.Price % 1 
      let upToDollar = cents > 0 ? (ps.Price + 1 - cents) : ps.Price 
      let upToHalfDollar = cents == 0 ? ps.Price : (cents < 0.5 ? (ps.Price + 0.5 - cents) : (ps.Price + 1 - cents)) 
      select new 
      { 
       FinalPrice = roundingId == 0 ? ps.Price : (roundingId == 1 ? upToDollar : upToHalfDollar) 
      }; 

Answer 2

如果你願意，你可以全部內聯，但說實話，看起來好像很難閱讀。試試這個：

int roundingId = 0; //0 = no rounding. 1 = dollar rounding. 2 = half-dollar rounding. 

    var prices = from ps in ObjectContext.Products 
    select new 
    { 
     FinalPrice = GetPrice((ps.IsCustomPrice ? ps.CustomPrice : ps.Retail), roundingId), 
    } 

private double GetPrice(double price, int roundingOption) 
{ 
    switch (roundingOption) 
    { 
     case 0: 
     //Do stuff 
     break; 
     case 1: 
     //Do stuff 
     break; 
     case 2: 
     //Do stuff 
     break; 
    } 
}