Wait for http inside Guard on Angular 5

So, first thing first: avoid the use of any when possible, specially when you know which type belongs where.

export interface FooInterface {
  status: string;
  fooString : string;
  fooNumber : number;
}

First Ill define the interface of the service in a clean manner, and then Ill refactor the guard class.

UPDATED ANSWER for rxjs 6.x

import { throwError, Observable } from 'rxjs';
import { catchError } from 'rxjs/operators';

@Injectable()
export class FooService {
   constructor(private _http: HttpClient) {}

   public apiGet(url: string): Observable<FooInterface> {
    return this._http
        .get<FooInterface>(this.apiUrl + url)
        .pipe(
          catchError(error => {
             // do general error handling if necessary and throw
            throwError(error);
           })
        );
  }
}

The guard class:

import { of, Observable } from 'rxjs';
import { map, catchError } from 'rxjs/operators';

@Injectable()
export class ResolveGuard implements CanActivate {
constructor(
    private fooService: FooService ,
) { }

canActivate(): Observable<boolean> {
    return this.fooService.apiGet('my/url')
       .pipe(
         map(response => response.status === 'success'),
         catchError(error => of(false))
       );
}

ORIGINAL ANSWER for rxjs 5.x

import { _throw } from 'rxjs/observable/throw':

constructor(private _http: HttpClient) {}

public apiGet(url: string): Observable<FooInterface> {
    return this._http
        .get<FooInterface>(this.apiUrl + url)
        .catch(error => {
          // do general error handling if necessary and throw
          _throw(error);
       });
}

The guard class:

import { of } from 'rxjs/observable/of';

@Injectable()
export class ResolveGuard implements CanActivate {
constructor(
    private _api: ApiService,
) { }

canActivate(): Observable<boolean> {
    return this._api.apiGet('my/url')
       .map(response => {
          let val = false;
          if ( response.status === 'success') {
                // Consume data here
                val = true;
          }
          return val;
        }).catch(error => {
          // consume the error maybe?
          of(false)
        });
}

just import map operator and it will work :

import { Observable } "rxjs/Observable"; 
import "rxjs/add/operator/map"; 

 canActivate(): Observable<boolean>{
        return this._api.apiGet('my/url').map(response => {
            if ( response.status === 'success') {
                // Consume data here
                return true;
            }
            return false;
        });
    }