Asp .Net MVC, why my viewbag always not null?

Question

I have assigned some data from database table into my viewbag in controller. Since there is no containing data, my viewbag returns true. Why is this happened?

Controller

//bear in mind that there is no status == 1, all were status == 0
Viewbag.itemlist = db.Furnitures.Where(x => x.Status == 1).ToList();

View

@if(Viewbag.itemlist != null)
{
   //The string is displayed even tho it does not contain any data
   <p>I appear</p>
}

Because your query cannot return null - its returns an empty collection — user3559349
– user3559349, Commented Jun 13, 2018 at 9:09
@if(Viewbag.itemlist.Any()) or @if(Viewbag.itemlist.Count > 0) — user3559349
– user3559349, Commented Jun 13, 2018 at 9:13
You can just count how many items are in the list to know if it's empty. To make a real-world analogy: How do you know if your shopping bag is empty? You'd count the items in it, of course. And an empty shopping bag is different from not actually having a bag at all (this scenario would be the equivalent of null in the code) — ADyson
– ADyson, Commented Jun 13, 2018 at 9:17

GiampaoloGabba · Accepted Answer · 2018-06-13 09:41:10Z

3

If you want to check if a List is empty, try this:

@if( ((List<Furnitures>) Viewbag.itemlist).Count > 0)
{
    //The string is displayed even tho it does not contain any data
    <p>I appear</p>
}

or

@if( ((List<Furnitures>) Viewbag.itemlist).Any())
{
    //The string is displayed even tho it does not contain any data
    <p>I appear</p>
}

Update:

As pointed out by @learnprogramming, the second solution doesn't work. .Any() doesn't operate on a List, it operates on an IEnumerable.

To make it works you need to add

@using System.Linq

to the top of your view file. Thanks to @ColinM for the tip.

Update 2

Another tip from @Colin. MVC has full support for model binding between Controllers and Views.

It's way better to pass data with model binding instead of ViewBag. In your ActionResult you should do this:

var furnituresList = db.Furnitures.Where(x => x.Status == 1).ToList();
return View(furnituresList);

Then in your view put this on top (after the @using directives):

@model List<Furnitures>

And then check with this:

@if(Model.Count > 0)
{
    //The string is displayed even tho it does not contain any data
    <p>I appear</p>
}

edited Jun 13, 2018 at 9:41

answered Jun 13, 2018 at 9:15

GiampaoloGabba

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3 Comments

LearnProgramming Over a year ago

the second solution does not work though...error saying does not contain a definition for 'Any''...the other solution work fine

ColinM Over a year ago

The second solution actually will work if you add @using System.Linq to the top of your view file. Any() is an extension method of IEnumerable<T> which List<T> implements.

ColinM Over a year ago

Another recommendation would be to provide an option in your answer for Model binding, rather than using ViewBag and casting. What if itemList isn't a List<Furnitures> due to developer error at some point ;-)

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