Type 'Promise<string[]>' is not assignable to type 'string[]'

Question

Getting following error: Type 'Promise<string[]>' is not assignable to type 'string[]'. Property 'includes' is missing in type 'Promise<string[]>'.

when i cast Promise<string[]> to type 'string[]' My code below,

Component: app.dashboard.ts

    import {Component} from '@angular/core';     import { MemberService } from "./app.service";     @Component({     selector:'app-root',     templateUrl:'./app.dashboard.html',     providers:[MemberService]               })      export class AppDashboard{       title='Dashboard'       constructor(private memberService: MemberService) { }        public doughnutChartLabels:string[] =          this.memberService.getmemberheader();//error occurred here       }     } 

Service:app.service.ts

    import { Injectable } from '@angular/core';     import { Member } from './Member';     import { Http, Response, Headers, RequestOptions, URLSearchParams } from'@angular/http';     import 'rxjs/add/operator/map';     import 'rxjs/add/operator/toPromise';      @Injectable()     export class MemberService     {       constructor(private http: Http) {       }            private getHeaders(){         // I included these headers because otherwise FireFox         // will request text/html instead of application/json         let headers = new Headers();         headers.append('Accept', 'application/json');         return headers;       }              getmemberheader(): Promise<string[]> {         return this.http             .get(`/ReportService/MemberDatabaseCountryname`, {headers: this.getHeaders()})             .toPromise()             .then(this.extractData)             .catch(this.handleError);       }          private extractData(res: Response) {         let body = res.json();                 return body || {};       }       private handleError(error: any): Promise<any> {         console.error('An error occurred', error);         return Promise.reject(error.message || error);       }     } 

Answer 1

Assume your response from http.get is an array, here you are returning Promise from function memberService.getmemberheader, you should retrieve result of promise at its then callback instead (not assigning promise itself to array doughnutChartLabels).

public doughnutChartLabels: string[];  this.memberService.getmemberheader().then(res => {   this.doughnutChartLabels = res; })