How to bypass an argumentNull exception without modifying the database?

Question

I have an image property in my model, which sometimes migh be empty. The problem is that when there is no image in the database I gat an argumentNull exception. What I'd like to achieve is still to display the rest of the properties if there is no image in the record.

For the purpose I tried doing something like this in my view, which didn't work :

<div>
<h4>Company</h4>
<hr />
<dl class="dl-horizontal">
    <dt>
        @Html.DisplayNameFor(model => model.ImageData)
    </dt>
    @if (Model.ImageBase64 != null || Model.ImageData!= null )
    {
        <dd>

            <img src="data:image/png;base64,@Model.ImageBase64" />


        </dd>
    }
    <dt>
        @Html.DisplayNameFor(model => model.CompanyName)
    </dt>

    <dd>
        @Html.DisplayFor(model => model.CompanyName)
    </dd>

My model looks like this :

public class Company
{
    [Key]

    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

    public int CompanyId { get; set; }
    public byte[] ImageData { get; set; }
    [NotMapped]
    public HttpPostedFileBase UploadImage { get; set; }
    [NotMapped]
    public string ImageBase64 => System.Convert.ToBase64String(ImageData);
    public string CompanyName { get; set; }
    public string CompanyAddress { get; set; }
    public string CompanyCountry { get; set; }
    public string CompanyCity { get; set; }
    public string CompanyPostalCode { get; set; }
    public string CompanyPhoneNumber { get; set; }
    public string CAId { get; set; }
    public virtual ICollection<WorkRole> WorkRoles { get; set; }
    public virtual ICollection<UserDetails> UserDetails { get; set; }
}

And this is what I pass to the view from the controller :

Company company = db.Companies.Where(c => c.CAId == currentUserId)
                .FirstOrDefault();
        db.Users.FirstOrDefault(x => x.Id == currentUserId);

Any tips on how to achieve what I want?

Are you returning a model to the view - the only way the code you have shown could throw an exception is is `Model` is `null` — , Feb 11 '17 at 11:19
Then you have not shown us the code which is really throwing the exception. The `@if (Model.ImageBase64 != null || Model.ImageData!= null )` is not even required — , Feb 11 '17 at 11:26
I though I showed you the code that is throwing it..What else it might be if not the view or the controller? The exception is thrown, because string ImageBase64 is not nullable and i want to bypass that. Excuse my noobnes. — Robert Ross, Feb 11 '17 at 11:30
The issue is not the view - its `public string ImageBase64 => System.Convert.ToBase64String(ImageData);` - the `ToBase64String(null)` throws the exception — , Feb 11 '17 at 11:38
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/135442/discussion-between-stephen-muecke-and-robert-ross). — , Feb 11 '17 at 11:43

Darren · Accepted Answer · 2017-02-11T11:41:17.370

1

You could perform a null check and ensure that the ImageData property is valid before rendering it in the View.

if (@model.ImageData?.Length > 0) { }

You could also take it one step further and modify your LINQ query to filter companies that have a valid image.

 db.Companies.Where(c => c.CAId == currentUserId
                    && c.ImageBase64 != null
                    && c.ImageData?.Length > 0).FirstOrDefault();

As an additional note, ensure you are passing a populated model back to your view correctly.

public ActionResult DisplayCompanyImages() 
{
    var model = // Retrieve db.Companies
    return View(model);
}

edited Feb 11 '17 at 11:41

answered Feb 11 '17 at 11:19

Darren

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The exception is not because `ImageBase64` is `null` - its because `Model` is `null` – Feb 11 '17 at 11:23
Thanks for the answer. I tried it, but it gave me the following exception : LINQ to Entities does not recognize the method 'Boolean IsNullOrWhiteSpace(System.String)' method, and this method cannot be translated into a store expression. – Robert Ross Feb 11 '17 at 11:24
@RobertRoss - I've amended my answer to show a LINQ to Entities replacement for `.IsNullOfWhiteSpace` – Darren Feb 11 '17 at 11:29
@StephenMuecke - OP hasn't provided any code showing what model they are returning to the View and stated they have a populated model. I have also included it in my answer as a safe check. – Darren Feb 11 '17 at 11:30

score 1 · Answer 2 · answered Feb 11 '17 at 11:26

If you are using Database First, open your Model (*.edmx file), find the entity type that represents the database table, right-click on the image property and select Properties from the context menu. In the Properties window, change Nullable from False to True.

How to bypass an argumentNull exception without modifying the database?

2 Answers2