轉換爲表達

Question

我怎麼能這種方法轉換爲表達我可以在使用LINQ到實體：

public bool IsMatch(long additionId) 
    { 
     return AdditionsPrices.Any(x => x.AdditionId == additionId); 
    } 

謝謝！

Answer 1

這就是：

List<long> additionIds = AdditionsPrices.Select(x => x.AdditionId) 
             .ToList(); 

，然後在EF Contains()查詢使用解決方案：

public Expression<Func<Addition, bool>> IsMatch(long additionId) 
    { 
     return a => a.AdditionsPrices.Any(x => x.AdditionId == additionId); 
    } 

Answer 2

爲什麼你不只是做了一個contains（）查詢，而不是 - 提取List<long>從AdditionsPrices：

var results = context.SomeEntitySet 
        .Where(x => additionIds.Contains(x.AdditionId));