import { Injectable } from '@angular/core' ; export interface City { id : number ; name : string ; postCode : number ; } @ Injectable ( ) export class CityService { getCities ( ) { return [ { id : 1 , name : 'Ho Chi Minh' , postCode : 700000 } , { id : 2 , name : 'Ha Noi' , postCode : 100000 } , { id : 3 , name : 'Da Nang' , postCode : 550000 } ] ; } }