DbContext已被处置 [英] DbContext has been disposed

问题描述

我用ASP.NET MVC 4和SQL Server 2008开发了一个Web应用程序，我创建了ContextManager类，以便在所有页面中只有一个数据库上下文.

I developed a web application with ASP.NET MVC 4 and SQL Server 2008, I create ContextManager class to have only one database context in all pages.

public static class ContextManager
{
    public static HotelContext Current
    {
        get
        {
            var key = "Hotel_" + HttpContext.Current.GetHashCode().ToString("x")
                      + Thread.CurrentContext.ContextID.ToString();
            var context = HttpContext.Current.Items[key] as HotelContext;
            if (context == null)
            {
                context = new HotelContext();
                HttpContext.Current.Items[key] = context;
            }
            return context;
        }
    }
}

它在大多数页面上都能正常工作，但是在注册页面上出现了问题，我的上下文被以下错误所取代:

It works properly in most of the pages, but in registration page something goes wrong and my context gone deposed with following error:

由于已处理DbContext，因此无法完成该操作.

The operation cannot be completed because the DbContext has been disposed.

public ActionResult Register ( RegisterModel model )
{
    if ( ModelState.IsValid )
    {
        // Attempt to register the user
        try
        {
            WebSecurity.CreateUserAndAccount( model.UserName, model.Password,
                                              new
                                               {
                                                      Email = model.Email,
                                                      IsActive = true,
                                                      Contact_Id = Contact.Unknown.Id
                                               } );

            //Add Contact for this User.
            var contact = new Contact { Firstname = model.FirstName, LastName = model.Lastname };
            _db.Contacts.Add( contact );
            var user = _db.Users.First( u => u.Username == model.UserName );
            user.Contact = contact;
            _db.SaveChanges();
            WebSecurity.Login( model.UserName, model.Password );

在行_db.Contacts.Add( contact );处出现了异常.

但无需通过更改使用ContextManager

But without using ContextManager by changing

HotelContext _db = ContextManager.Current;

进入:

HotelContext _db = new HotelContext();

问题已解决.但是我需要使用自己的ContextManager.有什么问题吗?

the problem was solved. But I need to use my own ContextManager. What is the problem?

推荐答案

您的上下文已放置在其他地方(不在您显示的代码中)，因此，基本上，当您从Register动作访问它时，它会抛出例外.

Your context has been disposed somewhere else (not in the code you've shown), so basically when you access it from your Register action, it throws the exception.

实际上，您不应使用静态单例来访问上下文. 为每个请求实例化一个新的DbContext实例.请参阅使用Entity Framework的c#在多线程服务器中

Actually, you shouldn't use a static singleton to access to your context. Do instantiate a new DbContext instance for each request. See c# working with Entity Framework in a multi threaded server

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