C # Linq Group By 在多列上

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; }
}

给定上面的两个类，我想使用 LINQ 从 List 中创建一个 List，按 School、 Friend 和 FavoriteColor 属性分组。LINQ 可以做到这一点吗？

请忽略这些属性，编写这些代码只是为了帮助解决这个问题。

725046

小开

给定一个列表:

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"},
};

查询如下所示:

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()
}
);

测试代码:

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

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(), };

var consolidatedChildren = children .GroupBy(c => new { c.School, c.Friend, c.FavoriteColor, }) .Select(gcs => new ConsolidatedChild() { School = gcs.Key.School, Friend = gcs.Key.Friend, FavoriteColor = gcs.Key.FavoriteColor, Children = gcs.ToList(), });