使用LINQ

Question

選擇一個物業的第一記錄我有一個類

class Test 
{ 
    public string FirstProp { get; set; } 
    public string SecondProp { get; set; } 
    public string ThirdProp { get; set; } 
} 

和對象

var list = new List<Test> 
{ 
    new Test { FirstProp = "xxx", SecondProp = "x2", ThirdProp = "x3" }, 
    new Test { FirstProp = "xxx", SecondProp = "x21", ThirdProp = "x31" }, 
    new Test { FirstProp = "yyy", SecondProp = "y2", ThirdProp = "y3" }, 
    new Test { FirstProp = "yyy", SecondProp = "y21", ThirdProp = "y31" }, 
    new Test { FirstProp = "xxx", SecondProp = "x22", ThirdProp = "x32" }, 
}; 

我需要選擇第一FirstProp記錄列表：

FirstProp = "xxx", SecondProp = "x2", ThirdProp = "x3" 
FirstProp = "yyy", SecondProp = "y2", ThirdProp = "y3" 

如何以最好的方式使用linq？

Answer 1

您可以在屬性FirstProp使用GroupBy，然後就得到First：

list.GroupBy(x => x.FirstProp).Select(g => g.First()) 

Answer 2

list.GroupBy (l => l.FirstProp).Select (l => l.First()) 

將在這裏工作，但你需要確定你需要從每個組有什麼項目（第一個是不始終是一個不錯的選擇）

Answer 3

您需要使用Distinct財產

var result = list.DistinctBy(t => t.FirstProp);