MVC4模型在查看问题中：在调试模式下模型缺少详细信息

Question

I encountered a very strange (and annoying) issue: in MVC 4 web application while loading data from the database and using a foreach on the Model within the view:

@foreach (var meeting in Model)

i have a breakpoint in the method's beginning and examining the object meeting i see that it misses some data (reference to other tables). if I open (+) other object within meeting the missing data appears.

Why?

Thanks!

here is my controller method:

        public ActionResult GetMeetingMR(int id = 0)
    {
        var meetingPurpose = db.MeetingPurposes.ToList();
        ViewBag.MeetingPurpose = new SelectList(meetingPurpose, "MeetingPurposeID", "MeetingPurposeName");
        ViewBag.MRID = id;
        List<Meeting> meetings = (db.MortgageRequests.Find(id)).Meetings.ToList();
        return View(meetings);

    }

Answer 1

Including your title in your question, my guess is you do not experience the problem (yet) without the debugger attached.
As others have commented it is due to LazyLoading .
The problem may occur sometimes because while rendering the View the entities container is being disposed, most probably because it is collected by the GarbageCollector which calls the destructor of the container.

If you wish to access the entities on your View you can use Include on the ObjectSet . Let's say MeetingPurposes has an associated EntitySet of Dates : If you wish to include them in the loadoperation you can do the following: db.MeetingPurposes.Include("Dates").ToList();

public ActionResult GetMeetingMR(int id = 0)
{
    //Load the MeetingPurposes including their dates
    var meetingPurpose = db.MeetingPurposes.Include("Dates").ToList();
    ViewBag.MeetingPurpose = new SelectList(meetingPurpose,
                                            "MeetingPurposeID",
                                            "MeetingPurposeName");
    ViewBag.MRID = id;
    List<Meeting> meetings = (db.MortgageRequests.Find(id)).Meetings.ToList();
    return View(meetings);
}

If you wish to do this for Meetings and Meetings has an EntitySet of Dates you could do:

public ActionResult GetMeetingMR(int id = 0)
{
    var meetingPurpose = db.MeetingPurposes.ToList();
    ViewBag.MeetingPurpose = new SelectList(meetingPurpose,
                                            "MeetingPurposeID",
                                            "MeetingPurposeName");
    ViewBag.MRID = id;
    var meetings = (from mee in db.Meetings.Include("Dates")
                    join mga in dbo.MortgageRequests.Where(m => m.Id == id)
                    on mee.MortgageRequestID equals mga.ID
                    select mee).ToList();
    return View(meetings);
}

Not really sure what your Find extension method is so I used a Where on MortgageRequests .