The type 'Promise <string []>' is not assigned to the type 'string []'

Question

Getting the following error: The type 'Promise' is not assigned to the type 'string []'. The 'includes' property is not in the 'Promise' type.

when I use Promise to enter 'string []' My code is 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
  }
}

Services: 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

Suppose your answer from http.getis an array, here you are returning Promisefrom a function memberService.getmemberheader, you should get the result of the promise when you call it back then(without assigning yourself to the array itself doughnutChartLabels).

public doughnutChartLabels: string[];

this.memberService.getmemberheader().then(res => {
  this.doughnutChartLabels = res;
})

Answer 2

@levolutionniste

getmemberheader() .

Async/Callback. ES6 Promise. , , .

:

getmemberheader()
.then((returnsAStringArrayObjectHere_YouCanCallItAnythingYouLike) => {
 // Do something with this array here
})
.catch((error) => {
 console.log("Oops something went wrong: ", error);
});

:

• https://basarat.gitbooks.io/typescript/docs/promise.html - .
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

getmemberheader string [].

this.memberService.getmemberheader().then(res => {
  this.doughnutChartLabels = res;
})

res [] getmemberhead. {} doughnutChartLabels res.

, ORM, , , .

.