Documentation doesn't speak of required properties for Blazor parameters

[NielsHoogeveen]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

When passing an instance of a reference type to a parameter in a blazor component, I can use someling like this:

[Parameter]
[EditorRequired]
public Model Model {get; set;}

This results in a warning that the property Model may be null.

Making the property required makes the warning go away. (Making it "init" prevents my code from accidentally updating the property).

[Parameter]
[EditorRequired]
public required Model Model {get; init;}

This seems to work and does everything I want. As far as I can tell, this behavior is not publically documenten, so I am not certain it will keep working in future versions of Blazor.

Describe the solution you'd like

Provide information in the documentation about the use of required and init for parameter and inject properties.

Additional context

No response

[Aculeo]

Nevermind, sorry - I didn't realize you were refering to using init

It is documented here: https://learn.microsoft.com/en-us/aspnet/core/blazor/components/?view=aspnetcore-6.0#component-parameters-1

if you scroll down further. It's not exactly prominent though.

[javiercn]

@NielsHoogeveen thanks for contacting us.

Required does nothing in Blazor, it's a compiler feature Blazor is not aware of, and can't enforce at runtime. The reason being that components are first instantiated and their parameters then set via a call to SetParametersAsync.

required means that the compiler will produce an error if you don't initialize the member right after the instance creation, which only applies for code you write on your app, not to code that uses reflection to instantiate your type and set members.

This is equivalent to how init is a compiler only feature that serializers and deserializers happily ignore.

[MackinnonBuck]

Closing out in favor of #47864