Error displaying details (ObjectContext instance has been disposed)

I'm building an ASP.NET MVC 3 app and I've got a model that looks something like so:

public partial class Flavor
{
   // ...
   public string Name { get; set; }
   public bool HasNuts {get; set; }
   public virtual ICollection<SaleData> Sales {get; set;}
   // ...
}

which retrieves some data from a db as such:

public PartialViewResult Details(int id)
{
   using (var db = new IceCreamDBFlavors())
   {
      Flavor someFlavor = db.Flavors.Find(id);
      someFlavor.Sales = db.Sales.Where(c => c.FlavorID == id).ToList();
      return PartialView("details", someFlavor);      
   }
}

over on the view I do something like this:

<fieldset>
   <legend>Sales Data</legend>
   @foreach (var sale in Model.Sales)
   {
      <div>Weekly</div>
      <div>@sale.Weekly</div>
   }
</fieldset>

If I don't retrieve the Sales data, my Flavor data displays fine with no errors, but adding the call to retrieve the list of sales data causes an error "The ObjectContext instance h开发者_Python百科as been disposed and can no longer be used for operations that require a connection." to occur.

I've read a few other posts about this and guess I'm missing something here. I believe this error happens due to lazy loading, at least based on what I've read here and elsewhere. Setting a breakpoint in the Controller before returning the PartialView and checking the object, I believe, causes the evaluation to take place, so everything displays as I would want.

I was under the impression that the ToList() call would force the Sales collection to be filled in. Since I don't have the issue when that line's commented out, I assume the problem is still related to that and when the View is attempting to iterate the Sales, it can't. Am I correct here? I guess I thought I was forcing the evaluation. How do I resolve this?

My suspicion is that Flavor has other collections (and not just Sales) and it is in fact at the time of accessing those that it breaks.

Here you are replacing only Sales while other collections or complex properties would still need the object context.

Don't dispose the IceCreamDBFlavors class that inherits from ObjectContext, it needs to have a lifetime greater than is currently allowed.

Change

using (var db = new IceCreamDBFlavors())
{
  Flavor someFlavor = db.Flavors.Find(id);
  someFlavor.Sales = db.Sales.Where(c => c.FlavorID == id).ToList();
  return PartialView("details", someFlavor);      
}

To

try
{
    var db = new IceCreamDBFlavors();

    Flavor someFlavor = db.Flavors.Find(id);
    someFlavor.Sales = db.Sales.Where(c => c.FlavorID == id).ToList();
    return PartialView("details", someFlavor);    
}
catch(Exception ex)
{
    // log exeption
}