PanelMenu#model does not support immutable objects (signalState)

[robmanganelly]

Describe the bug

PanelMenu#model requires an array of MenuItem elements, but if this array is coming from an immutable source (signalState) the component will not update the state on user interactions, and it will try to mutate the object, which causes a TypeError

I forked the repo, but at the moment can't submit a PR, I sincerely apologize. I will revisit this issue later and will contribute if it is still open.

Hacky Patch

This should be a temporary patch for consumers that are required to use immutable objects

If you cannot change the component and are required to use reactive state, or any other immutable object, you can use this patch

// excerpt from Myservice.ts
private state = signalState<TState>({
    //...other props
    menu: navItems, // default value
  });

  readonly opened = this.state.opened;

  // readonly menu = this.state.menu; // replace to this once the bug is fixed
  get menu() {
    return JSON.parse(JSON.stringify(this.state.menu()));
  }
  set menu(menu: TState['menu']) {
    patchState(this.state, { menu });
  }

then in the component

export class MyComponent {

  #nav = inject(MyService);

  readonly menu = this.#nav.menu;  //MenuItem[]

  //...rest of the code
}

Why
signalState objects have been frozen recursively, so the only "easy" way to defrost them is to create a new object. Spread operator create shallow copies (won't work)

Important
do not create that getter/setter in the component because signals trigger change detection cycles and that would cause an infinite loop. This is expected to happen in the data layer.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

No response

Reproducer

https://stackblitz.com/edit/github-tamhkczt

Environment

nx workspace +
angular19 + ngrx/signals@19

Angular version

19.x.x

PrimeNG version

v19

Node version

22.x.x

Browser(s)

Chrome

Steps to reproduce the behavior

1. Open the console
2. Click any menu option
3. you should see an error in console TypeError
4. menu won't open

Expected behavior

When the user clicks the options, the menu should open if it has children