Linq中的层次化
Linq中的层次化
提问于 2010-06-23 12:40:01
如果我有一组与以下类似的雇员数据：
var users = new[]
{
new {SupervisorId = "CEO", UserId = "CEO", UserName = "Joe"},
new {SupervisorId = "CEO", UserId = "CIO", UserName = "Mary"},
new {SupervisorId = "CIO", UserId = "XDIR", UserName = "Ed"},
new {SupervisorId = "CIO", UserId = "YDIR", UserName = "Lisa"},
new {SupervisorId = "XDIR", UserId = "AMNGR", UserName = "Steve"},
new {SupervisorId = "AMNGR", UserId = "ASUP", UserName = "Lesley"}
};是否可以使用Linq添加分层层，即：
- 首席执行官=1 (top)
- CIO =2(2级)
- XDIR和YDIR =3(Etc)
- AMNGR=4(Etc)
H 110ASUP=5(Etc)H 211F 212
我已经能够根据SupervisorId对员工进行分组，但不确定如何实现“级别”。
var userGroups = from user in users
group user by user.SupervisorId into userGroup
select new
{
SupervisorId = userGroup.Key,
Level = ??????
Users = userGroup.ToList()
};
foreach (var group in userGroups)
{
Console.WriteLine("{0} - {1} - {2}", group.SupervisorId, group.Level, group.Users.Count);
}非常感谢。
回答 4
Stack Overflow用户
发布于 2010-06-23 12:59:21
我会给你的linq“用户对象”添加一个排名。
public class User{
public string SupervisorId {get;set;}
public string UserId {get;set;}
public string UserName {get;set;}
public int Level {get { return GetRank(SupervisorId ) ; } }
private int GetRank(string userId){
if(string.IsNullOrEmpty(userId)){
//Bad case, probably want to use a very large number
return -1;
}
int level = 0;
switch(userId){
case "CEO":
level = 0;
break;
//insert others here
}
}
}然后你的Linq，你会添加一个连接。
var userGroups = from user in users
join super in users on user.SupervisorId equals super.UserId
group user by user.SupervisorId into userGroup
select new
{
SupervisorId = userGroup.Key,
Level = super.Level,
Users = userGroup.ToList()
};Stack Overflow用户
发布于 2010-06-23 13:09:27
更新
以下是为每个级别创建查找表的一种方法。这是公平的，我不知道它将如何扩大。显然，您需要对其进行调整，以便从数据库中提取行。
定义一个类来保存我们的查找表
public class user{
public string SupervisorId;
public string UserId;
public int Level;
}然后，我们得到一个用户and /SupervisorId组合的唯一列表，然后循环遍历列表，通过“遍历”树来计算每个组合的级别。
var uniqueusers = (new user[]
{
new user {SupervisorId = "CEO", UserId = "CEO"},
new user {SupervisorId = "CEO", UserId = "CIO"},
new user {SupervisorId = "CIO", UserId = "XDIR"},
new user {SupervisorId = "CIO", UserId = "YDIR"},
new user {SupervisorId = "XDIR", UserId = "AMNGR"},
new user {SupervisorId = "AMNGR", UserId = "ASUP"}
}).Distinct();
foreach (var item in uniqueusers)
{
int level = 0;
user CurrentUser = item;
while (CurrentUser.UserId != CurrentUser.SupervisorId){
CurrentUser = uniqueusers.Where(c => c.UserId == CurrentUser.SupervisorId).FirstOrDefault();
level++;
}
item.Level = level;
}现在，您可以使用uniqueuser作为查找表来确定查询的级别。例如
private int GetLevel(string userId){
return uniqueusers.Where(c => c.UserId == userId).FirstOrDefault().Level;
}您甚至可以将其结合到一个步骤中，只需付出一点点努力。
Stack Overflow用户
发布于 2010-06-23 13:26:47
ILookup<string, User> subordLookup = users
.ToLookup(u => u.SupervisorId);
foreach(User user in users)
{
user.Subordinates = subordLookup[user.UserId].ToList();
}
User userHierarchy = user.Single(u => u.UserId == "CEO");免责声明：
CEOs.
- Preserves
- 不处理背后的多个循环relationships.
- Leaves孤儿。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/3101642
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