How do make ionic app detect change when update is made?

Ionic Framework Ionic Angular
2

Please read this post which covers the fundamental issue you’re having here and introduces the watch/peek/poke idiom I like to deploy in situations like this. You do not want to be manually instantiating Promises, read this for more on HttpParams which are a safer and more readable way to deal with query strings than what you currently have.

export interface Customer {
  id: string;
  last_name: string;
  first_name: string;
  email: string;
}

import {isString, isObjectLike} from "lodash-es";

class CustomerService {
  private customer$ = new BehaviorSubject<Customer | undefined>(undefined);
  private apiParams = new HttpParams();

  constructor(private http: Http, private storage: Storage) {
    this.storage.ready()
      .then(() => this.storage.get("custid"))
      .then(cust => this.customer$.next(cust));
    this.apiParams = this.apiParams.set("consumer_key", WHATEVER_GOES_HERE);
    this.apiParams = this.apiParams.set("consumer_secret", MORE_WHATEVER);
  }

  private customerUrl(custid: string): string {
    return `${SITE_URL}${WOOCOMMERCE_PATH}customers/${id}`;
  }

  peekCustomer(): Customer | undefined {
    return this.customer$.value;
  }

  watchCustomer(): Observable<Customer | undefined> {
    return this.customer$; 
  }

  pokeCustomer(cust: Customer | string | undefined): Observable<Customer | undefined> {
    if (isString(cust)) {
      // retargeting new customer id
      this.storage.set("custid", cust);
      return this.http.get(this.customerUrl(cust), {params: this.apiParams})
        .pipe(tap(custo => this.customer$.next(custo));
    } else if (isObjectLike(cust)) {
      // updating existing customer
      return this.http.put(this.customerUrl(cust.id), cust, {params: this.apiParams})
        .pipe(map(() => cust), tap((custo) => this.customer$.next(custo));
    } else {
      // clearing
      this.storage.remove("custid");
      this.customer$.next(undefined);
      return of(undefined);
    }
  }
}