C＃Linq Group By多列

public class ConsolidatedChild { public string School { get; set; } public string Friend { get; set; } public string FavoriteColor { get; set; } public List<Child> Children { get; set; } } public class Child { public string School { get; set; } public string Name { get; set; } public string Address { get; set; } public string Friend { get; set; } public string Mother { get; set; } public string FavoriteColor { get; set; } } 

鉴于上面的两个类，我想使用LINQ来创build列表，由学校，朋友和FavoriteColor属性分组。 这可能与LINQ？

请忽略这些属性，代码只是为了帮助解决这个问题。

Answer 1

简单：

 var consolidatedChildren = from c in children group c by new { c.School, c.Friend, c.FavoriteColor, } into gcs select new ConsolidatedChild() { School = gcs.Key.School, Friend = gcs.Key.Friend, FavoriteColor = gcs.Key.FavoriteColor, Children = gcs.ToList(), }; 

Answer 2

给出一个列表：

 var list = new List<Child>() { new Child() {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "John"}, new Child() {School = "School2", FavoriteColor = "blue", Friend = "Bob", Name = "Pete"}, new Child() {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "Fred"}, new Child() {School = "School2", FavoriteColor = "blue", Friend = "Fred", Name = "Bob"}, }; 

该查询将如下所示：

 var newList = list.GroupBy(x => new {x.School, x.Friend, x.FavoriteColor}) .Select(y => new ConsolidatedChild() { FavoriteColor = y.Key.FavoriteColor, Friend = y.Key.Friend, School = y.Key.School, Children = y.ToList() } ); 

testing代码：

 foreach(var item in newList) { Console.WriteLine("School: {0} FavouriteColor: {1} Friend: {2}", item.School,item.FavoriteColor,item.Friend); foreach(var child in item.Children) { Console.WriteLine("\t Name: {0}", child.Name); } } 

结果：

 School: School1 FavouriteColor: blue Friend: Bob Name: John Name: Fred School: School2 FavouriteColor: blue Friend: Bob Name: Pete School: School2 FavouriteColor: blue Friend: Fred Name: Bob