不能使用LINQ的使用嵌套类List<>有关MongoDB C＃ [英] Cant use Linq with nested class List<> on MongoDb C#

问题描述

我有以下类：

public class Company
{
   [BsonId]
   public string dealerId = null;

   public List<Dealer> dealers = new List<Dealer>();
}

public class Dealer
{        
   public string dId = null;          
   public int dIndex = -1;

   public List<AutoStore> stores = new List<AutoStore>();
}

public class AutoStore
{
   public string type = null; 
   public  Dictionary<string, object> data = new Dictionary<string, object>();
}

我能够存储公司在蒙戈类对象与插入（）。问题是，当我搜索一个文件，并尝试使用LINQ上的列表与LT;> 项目。 。公司>（）
。凡（CPY =我不断地得到一个异常

I am able to store the Company class objects in Mongo with Insert(). The problem is when I search for a document and try to use LINQ on the List<> items. I constantly get an exception .

var query =  collection.AsQueryable<Company>()
                 .Where(cpy =>
                     cpy.dealers.Where(dlr => 
                         dlr.stores.Count == 1).Count() > 0) ;

运行这段代码中，我得到：

Running this code I get:

System.NotSupportedException：无法确定表达式的系列化
信息：Enumerable.Count

System.NotSupportedException: Unable to determine the serialization information for the expression: Enumerable.Count

我刚开始使用的今天蒙戈，但我认为在 LINQ 支持是比较成熟的。谁能告诉我，如果我可以做一个嵌套数组查询像我和 C＃和 LINQ ？

I just started using Mongo today, but I thought the LINQ support was more mature. Can anyone tell me if I can do a nested array query like I've done with C# andLINQ ?

当我删除其中（）上的任何的列表与LT;> ，也没有抛出异常。

As soon as I remove the Where() on any of the List<> , that exception isn't thrown

推荐答案

您的异常问题区域去是你的归宿之内做其中，语句。

Going by your exception the problem area is within where you are doing Where statements.

我在我的评论说。试着这样做：

As I said in my comment. Try to do:

var v = collection.AsQueryable<Company>().Where(cpy => cpy.Dealers.Any(dlr => dlr.Stores.Count == 1));

目前您正在做的事情，如：

You are currently doing something like:

var dealers = collection.AsQueryable<Company>().Select(cpy => cpy.Dealers);
var dealersWithStores = dealers.Where(dealer => dealer.Stores.Count == 1);

然后，您正在检查是否有任何通过调用计数和检查，如果是大于0，让您的布尔在那里设有专卖店经销商。所有这一切都与调用 IEnumerable.Any（）。看看这个工程？ ：）

You are then checking if there are any dealers with stores by calling count and checking if that is more than 0 to get your bool in the where. All of this is the same as calling IEnumerable.Any(). See if this works? :)

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