System.InvalidCastException: in ASP.NET MVC partial views
In the controller:
public ActionResult Index()
{
ViewData["page"] = 0;
return View(data);
}
public ActionResult More(long page = 0)
{
ViewData["page"] = page;
return View(data);
}
So, I have two views: Index.aspx and More.aspx. I created a partial view (PartialView.ascx) that is used in both of the views. Inside the partial view, it accessed both Model and ViewData. The strange thing (to me anyway) is that when I tried to cast ViewData["page"] to a long, I would get the following casting exception for one of the views:
System.InvalidCastException: Specified cast is not valid.
I tried to cast the ViewData["page"] like the following:
if ((long) ViewData["page"] > 1) { ... }
and
long page = (long) ViewData["page"];
if (page > 1) { ... }
Each of them would throw a casting exception in one view of the other (but not both).
One difference between Index.aspx开发者_开发问答 and More.aspx is that Index.aspx uses a master page, and More.aspx does not.
Would anyone have any suggestion what may be wrong? Please let me konw if I need to provide more details. BTW, I'm farily new to C# and ASP.NET MVC.
This line:
ViewData["page"] = 0;
is setting the value to be a boxed int
. You're trying to unbox it to a long
. The simplest way to avoid this is to box to a long
to start with:
ViewData["page"] = 0L;
... or use int
for your page number to start with. (Are you really going to get more than int.MaxValue
pages?)
精彩评论