延迟加载MySQL连接器

Question

我在Windows 7 x64上使用MySql 5.1.53和MySql Connector/Net 6.4.4进行Visual Studio 2008 C#.NET 3.5项目.在我的应用程序中,我查询我的数据库:

IQueryable<Zoo> my_query = from d in my_context_.MySet
                                  .Include("Foo")
                                  .Include("Bar")
                                  where d.Fuzz.Status == (int)Status.Pending
                                  orderby d.Order
                                  select d;

foreach (Zoo z in my_query)
{
    if (some_expression)
    {
        // Lazy load some more data from the query. This throws a 
        // MySqlException
        z.Something.Load();
    }
    else
    {
        // Lazy load some other data from the query. This also throws a 
        // MySqlException
        z.SomethingElse.Load();
    }
}

我得到的例外是:

System.Data.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> MySql.Data.MySqlClient.MySqlException: There is already an open DataReader associated with this Connection which must be closed first.

我真的更喜欢能够懒惰加载我的对象的其余部分,因为它需要它的元素.有没有办法做到这一点,或者我需要.Include()我的整个对象在原始查询中？

Answer 1

根据您收到的错误，您似乎仍然打开了用于从初始查询加载数据的连接，因此您无法在同一上下文中打开另一个连接。

首先尝试具体化您的查询，这样您在仍在加载初始批次数据时就不会尝试延迟加载：

var list = my_query.ToList();
foreach (Zoo z in list)
...