CODEWITHSUNDEEP
c#razor
Stian
Stian

Reputation: 1602

Check for null in razor view

I'm sending this viewmodel to a view:

public class ViewModelProductCategory
{
    public int Id { get; set; }
    public int? ParentId { get; set; }
    public string Title { get; set; }
    public int SortOrder { get; set; }
    public IEnumerable<ViewModelProductCategory> Children { get; set; }
    public List<ViewModelProduct> Products { get; set; }
    public List<ViewModelProduct> OrphanProducts { get; set; }
}

This is the (partial) view:

@foreach (var item in Model)
{
    <li>
        @item.Title (@item.Products.Count) // this causes problems if num of products = 0.
        <ul>
            @Html.Partial("_CategoryRecursive.cshtml", item.Children)
        </ul>
    </li>
}

Sometimes a product category don't have any products, and that causes a null reference exeption when I try to count them. How can I check for that?

Upvotes: 3

Views: 4844

Answers (2)

thmshd
thmshd

Reputation: 5847

A big benefit of View Models is the fact that they hold data especially for the View. We often include additional read-only properties to support easier handling in the View.

Example, in the View Model you add a Property like this:

public string ProductCountInfo
{
    get
    {
        return Products != null && Products.Any() ? Products.Count().ToString() : "none";
    }
}

In the View, you simple do:

@item.Title (@item.ProductCountInfo)

This keeps your View clean and simple.

EDIT

Removed "C#6" Version of Property, doesn't matter anyway

Upvotes: 4

Emre Kabaoglu
Emre Kabaoglu

Reputation: 13146

Just try like this;

@item.Title (@(item.Products != null ? item.Products.Count.ToString() : "No products"))

or you can use ?. operator for C# 6 or higher

@item.Title (@(item.Products?.Count.ToString() ?? "No products"))

Upvotes: 3

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