Handling Null exception when my Object is still empty

Question

How can I handle this null exception?

I have a button that dequeues the data from my static variable class

public ActionResult BtnNext()
{
        System.Threading.Thread.Sleep(1000);
        var first = MyQueue.todayQueue.Dequeue();
        MyQueue.todayQueue.Count();
        ViewBag.QueueItem = first;
        return View();
}

And here is my view, this shows the data that I dequeued.

@{
    var item = (Rosh.QueueMe.Web.Models.MyQueue)ViewBag.QueueItem;
}

@{
    if (item != null)
    {
        //Help here.
    }
}


   <p>@item.QueueNumber</p>

I still don't know how to handle when my viewbag is still empty / null.
Right now I get this error:

Object reference not set to an instance of an object. / item was null.

The code won't proceed to my index page since it is null.

Your `item != null` check is in one code block, but you are referencing it directly later on (`@item.QueueNumber`). — Brendan Green, May 21 '19 at 03:12
`if(ViewBag.QueueItem != null)` safeguard condition before casting or use `as` operator — Ehsan Sajjad, May 21 '19 at 03:13
You have a check if `item != null`, and then further below you output `item.QueueNumber` **without** checking if `item` is null or not. Wrap the output in an `if` block. — Brendan Green, May 21 '19 at 03:24

score 0 · Answer 1 · answered May 21 '19 at 03:15

0

You either need to check for null for ViewBag.QueueItem as well or use as for reference casting which takes care in case of ViewBag.QueueItem is not being set or is null. So you can adjust it like:

@{
    var item = ViewBag.QueueItem as Rosh.QueueMe.Web.Models.MyQueue;
}

now the item will be set to null in case of ViewBag.QueueItem is null

answered May 21 '19 at 03:15

Ehsan Sajjad

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its still say item was null – Carlo Toribio May 21 '19 at 03:20
the error is in my `
@item.QueueNumber
` – Carlo Toribio May 21 '19 at 03:22
You need to wrap that output in an `if` block that checks if `item` is null or not. – Brendan Green May 21 '19 at 03:23
or use null coleasing : `
@item?.QueueNumber
` – Ehsan Sajjad May 21 '19 at 03:24
can u provide me the proper code? im just a newbie – Carlo Toribio May 21 '19 at 03:38

Handling Null exception when my Object is still empty

1 Answers1