我想写这应该得到一个用户对象和消息的用户已经发布量的查询。我这样做以下方式：

I want to write a query which should get an user object and the amount of messages the user has posted already. I did this the following way:

var query = (from u in _db.Repository<User>()
             where u.IsDeleted != true
             select new UserWithMessagecount()
             {
                 User = u
                 MessageCount = GetUserMessageCount(u.Documents).Count(),
             });

我使用的方法，因为一些消息应该被过滤掉（在一个动态的方式）

为了简单起见，我会发布功能，无需排序逻辑（这仍然产生相同的错误）。

To keep things simple I'll post the function without sorting logic (which still produces the same error).

    private EntitySet<Document> GetUserMessageCount(EntitySet<Document> set)
    {
        return set;
    }

返回的错误是：

The error returned is:

方法'X'没有支持转换为SQL。

Method 'x' has no supported translation to SQL.

在如何解决这个问题的任何想法？

Any ideas on how to fix this issue?

推荐答案

使用语法来代替：

 var query = (from u in _db.Repository<User>()
             let MessageCount = GetUserMessageCount(u.Documents).Count()
             where u.IsDeleted != true
             select new UserWithMessagecount()
             {
                 User = u,
                 MessageCount = MessageCount
             });