如何使用实体框架关联来自多个上下文的对象

您必须使用相同的上下文(可以将上下文传递给getdefaultrole方法),或者重新考虑关系并扩展实体。

您只需传递上下文即可。。即:

void MyFunction()
{
    using (TCPSEntities model = new TCPSEntities())
    {
        EmployeeRoles er = model.EmployeeRoles.First(p=>p.EmployeeId == 123);
        er.Roles = GetDefaultRole(model);
        model.SaveChanges();
     }

}

private static Roles GetDefaultRole(TCPSEntities model)
{
    Roles r = null;
    r = model.Roles.First(p => p.RoleId == 1);
    return r;
}

    public void GuestUserTest()
    {
        SlideLincEntities ctx1 = new SlideLincEntities();
        GuestUser user = GuestUser.CreateGuestUser();
        user.UserName = "Something";
        ctx1.AddToUser(user);
        ctx1.SaveChanges();

        SlideLincEntities ctx2 = new SlideLincEntities();
        ctx1.Detach(user);
        user.UserName = "Something Else";
        ctx2.Attach(user);
        ctx2.SaveChanges();
    }

是-Entity Framework的V1不支持跨2个或更多上下文工作。

以防你还没有找到它,在EF上有一个很好的faq http://blogs.msdn.com/dsimmons/pages/entity-framework-faq.aspx

http://msdn.microsoft.com/en-us/library/cc853327.aspx ),这是一个相当大的性能打击。因此,将其包装在using()结构中不是一个好主意。我在项目中所做的是通过静态方法访问它,该方法始终提供相同的上下文实例:

    private static PledgeManagerEntities pledgesEntities;
    public static PledgeManagerEntities PledgeManagerEntities
    {
        get 
        {
            if (pledgesEntities == null)
            {
                pledgesEntities = new PledgeManagerEntities();
            }
            return pledgesEntities; 
        }
        set { pledgesEntities = value; }
    }

然后我像这样检索它:

    private PledgeManagerEntities entities = Data.PledgeManagerEntities;