C#•10mo ago

✅ What is reason of null! here?

I have this property in entity model:

[Required]
[MinLength(1)]
[MaxLength(100)]
public string Identity { get; set; } = null!;

[Required]
[MinLength(1)]
[MaxLength(100)]
public string Identity { get; set; } = null!;

19 Replies

SWEETPONYOP•10mo ago

should I use required attribute? can I just do: public required string Identity {get;set;}

Gramore•10mo ago

strings are nullable by default. Within a nullable context = null! indicates that the string value should be initialized If you are familiar with nullable value types int? for example it indicates that the int can be null. string is a reference type and it is therefore possible that the value could be null (no reference). You could think of it as every string is a string? https://stackoverflow.com/questions/54724304/what-does-null-statement-mean for a much better written explanation 😁 As for best practice i am not sure, but if you have nullable enabled on the project and you want to indicate the string should not be null then i'd imagine it is correct but YMMV on what people do out in the wild ~

Angius•10mo ago

It just shuts up the compiler about the property not being initialized in the constructor So it initializes it with null but also says "trust me bro, it's not null" And, yes required is the preferable way nowadays

Gramore•10mo ago

Does required also shut it up? I thought it was more for binding shenanigans?

Angius•10mo ago

It does, yes Because it enforces the property to be set

Gramore•10mo ago

Makes sense i guess, i didn't think the component model stuff interacted with the nullability stuff but it's nice that it does

Angius•10mo ago

[Required] attribute is not the same as required keyword The former does nothing

Gramore•10mo ago

We have a required keyword??

Angius•10mo ago

The latter enforces the property to be set Yes

MODiX•10mo ago

Angius

REPL Result: Failure

class Foo
{
    public required int Bar { get; set; }
}

var f = new Foo();

class Foo
{
    public required int Bar { get; set; }
}

var f = new Foo();

Exception: CompilationErrorException

- Required member 'Foo.Bar' must be set in the object initializer or attribute constructor.

- Required member 'Foo.Bar' must be set in the object initializer or attribute constructor.

Compile: 266.582ms | Execution: 0.000ms | React with ❌ to remove this embed.

Gramore•10mo ago

Oh C#11, dang i'm fallin behind

MODiX•10mo ago

Angius

REPL Result: Success

class Foo
{
    public required int Bar { get; set; }
}

var f = new Foo {
    Bar = 69,
};

class Foo
{
    public required int Bar { get; set; }
}

var f = new Foo {
    Bar = 69,
};

Compile: 300.918ms | Execution: 38.861ms | React with ❌ to remove this embed.

Gramore•10mo ago

Oh i understand you, you mean it's preferable to use the reuqired keyword I thought you were talking about the attr 😂

Angius•10mo ago

Yeah

Gramore•10mo ago

Oh but it also kills the new() constraint that's a little restrictive I mean probably fine and correct, but does limit you for some stuff

Angius•10mo ago

I mean, it does enforce the property to be set You cannot create an object without the property being set

Gramore•10mo ago

you can still activator it right?

Angius•10mo ago

If it allowed you to just new() up the object without setting the property... wouldn't make much sense, would it I mean, I guess? If you want to use reflections to break the correctness of your code lol

Gramore•10mo ago

Always 🙂

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✅ What is reason of null! here?