C# 使用 LINQ 从列表中返回对象的查询
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Query in returning Objects from List using LINQ
提问by Arun Selva Kumar
I have a List Say foo, which holds data of type Class A (containing members FName, LName, Total). I need to get the list of datas whose LName is "foobar".
我有一个 List Say foo，它包含 A 类数据（包含成员 FName、LName、Total）。我需要获取 LName 为“foobar”的数据列表。
I know this sounds a simple question, but this pisses me off! because the I will get the Members for returning the list in runtime.
我知道这听起来很简单，但这让我很生气！因为我将获得在运行时返回列表的成员。
Thanks in advance
提前致谢
EDIT : I am sorry Geeks, the List is Dyanamic the List is of Object type. I knows its of type Class A only during runtime
编辑：对不起，极客，列表是动态的，列表是对象类型的。我只在运行时知道它的 A 类类型
采纳答案by MarcinJuraszek
It can be easily done using LINQ:
使用 LINQ 可以轻松完成：
using System.Linq;
(...)
List<A> foo = GetFooList(); // gets data
List<A> fooBorItems = foo.Where(a = > a.FName == "foobar").ToList();
Or using syntax based query:
或者使用基于语法的查询：
List<A> fooBorItems = (from a in foo
where a.FName == "foobar"
select a).ToList();
For List<object>use Cast<T>extension method first. It will cast all source collection elements into A(and throw exception when it's not possible):
对于List<object>使用Cast<T>扩展方法第一。它将所有源集合元素转换为A（并在不可能时抛出异常）：
List<A> fooBorItems = foo.Cast<A>().Where(a = > a.FName == "foobar").ToList();
or OfType<A>(which will return only elements that can be casted, without exceptions for these that can't):
或OfType<A>（将只返回可以转换的元素，不能转换的元素也不例外）：
List<A> fooBorItems = foo.OfType<A>().Where(a = > a.FName == "foobar").ToList();
