javascript - 在 Angular 2 中订阅后未定义值，但在 templateurl 中它可以显示

Question

我尝试处理我的服务中的值，但它返回未定义的值。但奇怪的是，如果我直接访问模板，它就可以工作。

这是我的服务

import { Injectable }     from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable }     from 'rxjs/Observable';
import {Globals} from "../globals";
import 'rxjs/Rx';
import 'rxjs/add/operator/map';
import {DetailprodComponent} from './detailprod.component';
import {Home} from '../home/home';
import { ActivatedRoute,Router } from '@angular/router';

@Injectable()
export class DetailprodService {
    private id:string;
    constructor (private http: Http, private route: ActivatedRoute) {
        this.route.params.subscribe(params => {let   id = params['id'];this.id = id;});
    }

    getDetail(){
        return this.http.get(Globals.server+'/product/'+this.id)
                    .map(res=> res.json());
    }

}

在组件中，在 onInit 方法中我放入了

this.detailprodService.getDetail()
        .subscribe(details => this.product_rating = details.product_rating,
          error => this.errorMessage = <any>error);
this.getstars(this.product_rating);

然后如果在 HTML 中我输入 {{product_ rating}} 它会显示输出。但如果我在组件中进一步处理它，则会导致未定义的值。我将 Product_Rating 发送到方法 this.getstars(this.product_Rating)

getstars(x){
    alert(x)
    if (x == 2){
      alert("1");
      this.starspath ="imagemanagement/1stars.png";
    }else if (x == 4){
      alert("2");
      this.starspath ="imagemanagement/2stars.png";
    }else if (x == 6){
      alert("3");
      this.starspath ="imagemanagement/3stars.png";
    }else if (x == 7){
      alert("4");
      this.starspath ="imagemanagement/4stars.png";
    }else if (x == 10){
      alert("5");
      this.starspath ="imagemanagement/5stars.png";
    }
  }

任何答案都将受到高度赞赏......

Answer 1

尝试如下:

   this.detailprodService.getDetail()
            .subscribe(details => {
this.product_rating = details.product_rating;
this.getstars(this.product_rating);
}, error => this.errorMessage = <any>error);

您应该等待订阅来处理该值。