我使用Angular 6。
在我的component.ts文件中，我必须初始化graph，并在**ngOnIt（）**方法中这样做

@Component({
  selector: 'app-contact-detail',
  templateUrl: './contact-detail.component.html',
  styleUrls: ['./contact-detail.component.css']
})
export class ContactDetailComponent implements OnInit {

  contact_id: string;
  public graph_data_year;

  constructor(
    private activatedRoute: ActivatedRoute,
    private graphDataService: GraphDataService
  ) { }

  ngOnInit() {
    this.activatedRoute.params.subscribe(
      param => {
        this.contact_id = param['id'];
      }
    );

    /**
     * Get Amount Given Graph Data
     */
    this.graphDataService.get_data(this.contact_id).subscribe(
      res => {
        const data = [];
        res.forEach(e => {
          data.push(e.total);
        });
        this.graph_data_year = data;
        this._setGraphData();
      }
    );

    this.initializeGraph();
  }

  _setGraphData() {
    this.lineBigDashboardChartData[0]['data'] = this.graph_data_year;

    // this console here gives updated value in the console window, but no update on chart
    console.log(this.lineBigDashboardChartData);
  }

  /**
   * Graph
   */
  initializeGraph() {
    ...

    this.lineBigDashboardChartData = [
      {
        label: 'Data',
        ...
        ...
        data: this.graph_data_year
      }
    ];
    this.lineBigDashboardChartLabels = ['JAN', 'FEB', 'MAR', 'APR', 'MAY', 'JUN', 'JUL', 'AUG', 'SEP', 'OCT', 'NOV', 'DEC'];

    this.lineBigDashboardChartType = 'line';
  }

}

而component.html就像

<canvas baseChart id="bigDashboardChart"
   [datasets]="lineBigDashboardChartData"
   [labels]="lineBigDashboardChartLabels"
   [chartType]="lineBigDashboardChartType"></canvas>

但它不会使用this.graphDataService更新的graph_data_year的更新值更新图表。并显示空白图表。
console.log(this.lineBigDashboardChartData);更新数据后，在控制台窗口中打印更新的值，但图表数据未更新。
我怎样才能在组件中有一个basec变量，在更新时，在组件中使用它的每个地方都更新值？或者我如何在更新数据后刷新购物车？