如何从可观察的 http 请求中返回值并将其存储在局部变量中？

Question

I have a Url http://localhost:3000/users/1 that will return json:

{ "id": 1, "name": "David", "is_available": true }

then I want to make a method that return is_available (boolean). But this method below will return undefined. This seems weird for me that new to angular & observable.

checkIsAvailable(id): boolean {
        let available;
        http.get('http://localhost:3000/users/1').subscribe(user => {
                available = user.is_available;
        }
        return available;
}

If I console.log() inside the.subscribe(), user.is_available will return true. How to properly create method that return value from http request?

Answer 1

checkIsAvailable(id): Observable<boolean>{
        let available;
        return http.get('http://localhost:3000/users/1').pipe(map(user => {
                return user.is_available;
        }));
}

Subscribe in component

this.service.checkIsAvailable().subscribe((res)=>this.available = res);

Answer 2

UPDATE

it seems you can only return Promise from an async function

try the following

async checkIsAvailable(id): Promise<any> {
        return await http.get('http://localhost:3000/users/1').toPromise();
}

change the way you call this function

this.checkIsAvailable(id).then((res) => {
  console.log(res);

  // your code here

}