从可观察的数据中获取不同的数据

Question

我在学习角度时遇到了问题。当我从一个Observable获取数据时，在NgOnInit方法中，没关系，该方法带来了正确的值。可悲的部分是当我尝试在外面的任何地方进行访问时，它给了我一个未定义的数组。**

    @Component({
      moduleId: module.id,
      selector: 'operacao',
      templateUrl: './operacao.component.html',
      providers: [Operacao],
      styleUrls: ['./operacao.component.css']
    })
    export class OperacaoComponent implements OnInit {

      private _operacao: Operacao;
      private _operacoes: any[];


    public rows: Array<any> = [];
    private myserviceService: MyserviceService;
...


 constructor(myservice: MyserviceService) {
    this.length = 10;
    this.myserviceService = myservice;

  }
    ...

ngOnInit() {
 this.myserviceService.getOperacoes()
  .subscribe((operacao) => {
    this._operacoes = operacao; 
    //here i get the "right" value
     console.log(this._operacoes); 
    //Array(2) [Object, Object]
    //0:Object {id: 0, acao_id: 0, user_id: "1", …}
    //1:Object {id: 1, acao_id: 1, user_id: "1", …} 

myservice.ts

getOperacoes() {
      return this.http.get(this.url + 'operacoes').map(res => res.json());
   }

当我打电话时，在Subscribe（）

之外的任何地方

console.log(this._operacoes);

我得到了未定义的