使用 Linq 将对象列表分组为新的对象列表分组列表 [英] Using Linq to group a list of objects into a new grouped list of list of objects

问题描述

我不知道这在 Linq 中是否可行，但是这里...

I don't know if this is possible in Linq but here goes...

我有一个对象:

public class User
{
  public int UserID { get; set; }
  public string UserName { get; set; }
  public int GroupID { get; set; }
}

我返回一个可能如下所示的列表:

I return a list that may look like the following:

List<User> userList = new List<User>();
userList.Add( new User { UserID = 1, UserName = "UserOne", GroupID = 1 } );
userList.Add( new User { UserID = 2, UserName = "UserTwo", GroupID = 1 } );
userList.Add( new User { UserID = 3, UserName = "UserThree", GroupID = 2 } );
userList.Add( new User { UserID = 4, UserName = "UserFour", GroupID = 1 } );
userList.Add( new User { UserID = 5, UserName = "UserFive", GroupID = 3 } );
userList.Add( new User { UserID = 6, UserName = "UserSix", GroupID = 3 } );

我希望能够在上面的列表上运行 Linq 查询，按 GroupID 对所有用户进行分组.所以输出将是一个包含用户的用户列表列表(如果这有意义?).类似的东西:

I want to be able to run a Linq query on the above list that groups all the users by GroupID. So the output will be a list of user lists that contains user (if that makes sense?). Something like:

GroupedUserList
    UserList
        UserID = 1, UserName = "UserOne", GroupID = 1
        UserID = 2, UserName = "UserTwo", GroupID = 1
        UserID = 4, UserName = "UserFour", GroupID = 1
    UserList
        UserID = 3, UserName = "UserThree", GroupID = 2
    UserList
        UserID = 5, UserName = "UserFive", GroupID = 3
        UserID = 6, UserName = "UserSix", GroupID = 3

我已经尝试使用 groupby linq 子句，但这似乎返回了一个键列表，并且没有正确分组:

I've tried using the groupby linq clause but this seems to return a list of keys and its not grouped by correctly:

var groupedCustomerList = userList.GroupBy( u => u.GroupID ).ToList();

推荐答案

var groupedCustomerList = userList
    .GroupBy(u => u.GroupID)
    .Select(grp => grp.ToList())
    .ToList();

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