错误:ObjectContext实例已被释放,不能再用于需要连接的操作

Question

我在C#中使用asp.net和EF 4.

我有一个关联的DetailsView ObjectDataSource.

<asp:ObjectDataSource ID="uxEntityDataSourceAuthors" runat="server" 
        SelectMethod="GetAuthors" 
        TypeName="WebProject.Web.Cms.AdminCms.Sections.CmsContents.ContentInformation">
    </asp:ObjectDataSource>

这个方法的代码:

---

    public IEnumerable<CmsAuthor> GetAuthors()
    {
    if (Roles.IsUserInRole("CMS-AUTHOR"))
    {
    using (CmsConnectionStringEntityDataModel context = new CmsConnectionStringEntityDataModel())
    {
                            // Display all Authors for specific logged-in User.
                            // Get Guid for current logged-in User.
                            MembershipUser myLoggedinUser = Membership.GetUser();
                            Guid myUserGuid = (Guid)myLoggedinUser.ProviderUserKey;
                            // Get list of Authors filtering my current logged-in User.
                            var myAuthorsForAuthor = from a in context.CmsAuthors
                                                     where a.UserId == myUserGuid
                                                     orderby a.LastName ascending
                                                     select a;
                            return myAuthorsForAuthor.AsEnumerable();
                        }
                    }
                    return null;  
 }

---

当我运行代码时,我收到此错误:

 The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. 

知道我做错了什么以及如何解决它？

Answer 1

您在获取数据之前关闭了CmsConnectionStringEntityDataModel被调用者context.请记住,AsEnumerable()将返回一个惰性枚举器,当您返回并处理`context时,没有从源读取数据.

使用ToArray()(或ToList())确保在关闭源之前将数据存入内存.