C#•4y ago

What does null! do in EF CORE? [Answered]

Hi, I've used scaffold db to generate models from existing table and I noticed this interesting pattern

    public City City { get; set; } = null!;

    public City City { get; set; } = null!;

Keep in mind city_id must not be null so why does EF Core generate it with default value of null and what does ! mean after unll?

ero•10/11/22, 10:25 AM

https://learn.microsoft.com/dotnet/csharp/language-reference/operators/null-forgiving

! (null-forgiving) operator - C# reference

Learn about the C# null-forgiving, or null-suppression, operator that is used to declare that an expression of a reference type isn't null.

Eero https://learn.microsoft.com/dotnet/csharp/language-reference/operators/null-forg...

barcodeOP•10/11/22, 10:26 AM

I've read it but I still don't understand why does it set it to that when it will never be null

barcodeOP•10/11/22, 10:26 AM

since it is set as not null in table

barcodeOP•10/11/22, 10:27 AM

I mean from what I understand it is reverse null

barcodeOP•10/11/22, 10:27 AM

meaning never null

barcodeOP•10/11/22, 10:27 AM

if I'm correct ?

ero•10/11/22, 10:28 AM

it's just a code specific issue. if you don't assign anything to , you'll end up with the warning

ero•10/11/22, 10:28 AM

so you explicitly set a value to it so you don't get that warning

ero•10/11/22, 10:28 AM

at least that's how i understood it

ero•10/11/22, 10:29 AM

and since you can't just set to it (because is a non-nullable type, and assigning to it will come up with a different warning) you just tell it to ignore the fact that it's null

ero•10/11/22, 10:30 AM

maybe someone who knows EF more will correct me

barcodeOP•10/11/22, 10:30 AM

thank you, kinda confusing but scaffold probably didn't make a mistake

v0fbu1vm•10/11/22, 10:31 AM

You can do something like this

ero•10/11/22, 10:31 AM

(which is basically the same, because == for reference types)

ero•10/11/22, 10:31 AM

but if you prefer how it looks, for sure

AccordAPP•10/11/22, 11:54 AM

This post has been marked as answered!