下面是我的代碼,使用LINQ to SQL,執行時我得到一個錯誤消息,說「對象引用未設置爲對象的實例」。我加入了3個表Users,UsersinRoles和Roles.Userinroles是橋表。我使用連接來從兩個表中檢索數據,使用橋表我得到對象引用錯誤。關於Silverlight項目的Linq-SQL錯誤
public class Users : CollectionFactoryBase
{
public Users()
{
this.Summary = "Collection of Users";
}
public override Collection MakeCollection(CollectionRequestContext context)
{
UsersDataContext m_dataContext = new UsersDataContext();
const int maxItems_c = 150;
try
{
// string sessionvalue = HttpContext.Current.Session["SessionKey"] as string;
var Users = from p in m_dataContext.aspnet_Users
join t in m_dataContext.aspnet_UsersInRoles on
p.UserId equals t.UserId
join r in m_dataContext.aspnet_Roles on
t.RoleId equals r.RoleId
select new
{
UserName = p.UserName,
UserId = p.UserId,
RoleId = r.RoleId,
RoleName = r.RoleName,
userid = t.UserId,
roleid = t.RoleId
};
Collection collection = new Collection();
collection.Name = "Users";
foreach (var user in Users.Take(maxItems_c))
{
collection.AddItem(user.UserName, user.RoleName, null, null, null, null, null);
}
return collection;
}
catch (Exception ex)
{
return ErrorCollection.FromException(ex);
}
}
}
}
哪條線路導致錯誤? – GrandMasterFlush 2012-03-21 14:11:20
構建沒有錯誤,執行時會打開並出現此錯誤,但沒有明確顯示行 – newuser1555 2012-03-21 15:01:03
讓Visual Studio在拋出異常時中斷,它將在一分鐘內清除導致異常的原因。我敢打賭,你的'Collection'類不是猶太教。無論如何,什麼樣的弱類型是? .net通用集合是不是更好? – 2012-03-25 22:29:23