As I am doing angular heroes tutorial from angular documentation. I am getting an error
Object is possibly 'null'.
getHero(): void {
const id = +this.route.snapshot.paramMap.get('id');
this.heroService.getHero(id)
.subscribe(hero => this.hero = hero);
}
in hero-detail.component.ts
link for the whole code hero-detail component
I have seen so many answers that to make it false in config.json. I need help with how to solve this, but not suppressing it.
Thanks in Advance.
you can do it in two steps
getHero(): void {
const param=this.route.snapshot.paramMap.get('id');
const id = param?+param:0;
this.heroService.getHero(id)
.subscribe(hero => this.hero = hero);
}
This is due to the stray plus sign combined with the fact the item this.route.snapshot.paramMap.get('id') might actually be null according to the Typescript type system so it's not a legitimate operand for +.
I recreated the same error with this code at this playground
const thing:string|null;
function getHero() : void {
const id = +thing;
}
Note the line that says...
const id = +thing;
If the use of + was intended as per Elisio's comment below, then you need to do something to guard the command, so that getHero not run at all when id is null, or that a reliable substitute value is provided for the id before running it. So long as there's a possibility it's null then
Typescript can't guarantee the operation will complete. This is good because it forces you to do the checks and add the safety.
const id=thing?+thing:0
+"2"is 2 is like say Number("2")