Use Null Conditional Operator on property of Null Object

Question

Use Null Conditional Operator on property of Null Object

c# c#-6.0 entity-framework-core

Question

I would like to use the Null-Conditional Operator to check the SubscriptionExpires property below.

    public partial class Subscription
{
    [Key]
    public int SubscriptionId { get; set; }
    public string SubscriberId { get; set; }
    public DateTime? SubscriptionExpires { get; set; }

    public virtual ICollection<ApplicationUser> Users { get; set; }
}

A subscription is returned by

var subscription = _customersContext.Subscriptions.Where(s => s.SubscriptionId == user.SubscriptionId).FirstOrDefault();

However if Subscription is null, Subscription?.SubscriptionExpires returns a null reference exception, so we are still left with the old

if (subscription != null)

How do I use the Null-Conditional Operator to read a property when the parent object can be null?

Vague

Popular Answer

If you want that "var expiration" should never throw exception while using it as DateTime datatype you can use

var expiration = subscription?.SubscriptionExpires ?? DateTime.MinValue;

Banketeshvar Narayan

View more on Stack Overflow

i3arnon · Accepted Answer · 1/19/2016 7:27:20 AM

How do I use the Null-Conditional Operator to read a property when the parent object can be null?

You do it just as you did with Subscription?.SubscriptionExpires. This will not throw a NullReferenceException, but it will return DateTime?. If you try to use a the DateTime?'s value then you'll get an exception. So this will not throw:

var expiration = Subscription?.SubscriptionExpires;

But this may:

DateTime? expiration = Subscription?.SubscriptionExpires;
DateTime expiration.Value;

Use Null Conditional Operator on property of Null Object

Question

Fastest Entity Framework Extensions

Accepted Answer

Popular Answer

Performance

Expression Evaluator

Related