RavenDB 对列表属性进行 Map/Reduce
刚刚学习 Map/Reduce，我错过了一个步骤。我读过这篇文章（使用 .NET 客户端的 RavenDB Map-Reduce 示例 ）但无法完全跳转到我需要的内容。
我有一个对象：
public class User : IIdentifiable
{
public User(string username)
{
Id = String.Format(@"users/{0}", username);
Favorites = new List<string>();
}
public IList<string> Favorites { get; protected set; }
public string Id { get; set; }
}
我想要做的是获取所有用户的 Map/Reduce 收藏夹属性。像这样的东西（但这显然不起作用）：
Map = users => from user in users
from oil in user.Favorites
select new { OilId = oil, Count = 1 };
Reduce = results => from result in results
group result by result.OilId into g
select new { OilId = g.Key, Count = g.Sum(x => x.Count) };
例如，如果用户 1 有收藏夹 1, 2, 3，用户 2 有收藏夹 1,2，那么这应该返回 {{OilId=3, Count =1}, {OilId=2, Count = 2}, {OilId=1,Count = 2}}
当前代码产生异常： System.NotSupportedException : Node not support: Call
我觉得我 关闭。有什么帮助吗？
Just learning Map/Reduce and I'm missing a step. I've read this post ( RavenDB Map-Reduce Example using .NET Client ) but can't quite make the jump to what I need.
I have an object:
public class User : IIdentifiable
{
public User(string username)
{
Id = String.Format(@"users/{0}", username);
Favorites = new List<string>();
}
public IList<string> Favorites { get; protected set; }
public string Id { get; set; }
}
What I want to do is get Map/Reduce the Favorites property across all Users. Something like this (but this obviously doesn't work):
Map = users => from user in users
from oil in user.Favorites
select new { OilId = oil, Count = 1 };
Reduce = results => from result in results
group result by result.OilId into g
select new { OilId = g.Key, Count = g.Sum(x => x.Count) };
For example, if User1 has favorites 1, 2, 3 and User 2 has favorites 1,2, then this should return back {{OilId=3, Count =1}, {OilId=2, Count = 2}, {OilId=1,Count = 2}}
The current code produces an exception: System.NotSupportedException : Node not supported: Call
I feel like I'm close. Any help?
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评论（2）
我编写了一个复制您的代码的小应用程序，但我没有看到抛出的异常。请在此处查看我的代码：http://pastie.org/2308175。输出是
这是我所期望的。
I wrote a small application replicating your code, but I don't see the exception thrown. See my code here: http://pastie.org/2308175. The output is
which is what I would expect.
博尼格，
Map/Reduce 仅适用于跨文档进行聚合。对于这样的事情，通过执行以下操作会得到更好的服务：
MBonig,
Map/Reduce is only useful for doing aggregation across documents. For something like this, you would be served far better by doing something like: