I’m trying to use singals and computed in my new Angular project, but I’m running into a problem.

I have a computed value, which contains an id, which is a number. This id will be set by user interaction. Before that it is not set, so I tried setting it to null (or undefined).

public selectedId = computed() {
  var result: number | null = null;
  // do some computations
  return result;
}

Now I wanted to use this in the template.

<div *ngIf="selectedId() as id">Current id: {{ id}}</div>

But this only works if the id is not 0. As soon as it is zero it behaves as if it is null. I switched everything to number | undefined, but it resulted in the same problem. As far as I know there is only the special case of null >= 0 being true. But maybe something changed or signals and computed values work differently.

I know I can change it to -1 representing the “null” value, but I would like to know if there is some better solutions to use number | null or if that’s just something we have to life with.

Thank you very much.