NG0952: Input is required but no value is available yet.

[sysmat]

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

Yes

Description

NG0952 Input is required but no value is available yet.

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

export class UserComponent {
user = input.required<User>();
expired = signal<Date>(this.user()? this.user().expired: null);

changeExpired(){
  this.expired.set(new Date());
}

Please provide the environment you discovered this bug in (run ng version)

Angular CLI: 17.3.1
Node: 20.11.1
Package Manager: npm 10.2.4
OS: win32 x64

Angular: 17.3.1
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, localize, platform-browser
... platform-browser-dynamic, router, service-worker

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1703.1
@angular-devkit/build-angular   17.3.1
@angular-devkit/core            17.3.1
@angular-devkit/schematics      17.3.1
@schematics/angular             17.3.1
rxjs                            7.8.1
typescript                      5.4.3
zone.js                         0.14.4

Anything else?

if I try effect then I can not use this.expired.set

[JeanMeche]

Hi, required inputs can only be read after the component is init (after ngOnInit()). By invoking user in the property initialization you're accessing a signal that hasn't been set yet.

In your case it looks like expired should be a computed input.

[sysmat]

• this is very bad, can not use declarative programming
• computed signal dos not have set or update function

[JeanMeche]

Nested Signals (like DeepSignal from the signal Store) might me a good fit for you.

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