订阅时无法在 ngoninit 中获取值 angular

Question

我不明白为什么我的对象在 angular 上的 ngoninit 上总是 "undefinned"。我请求我的 api 项目，我得到了正确的回复。当我 console.log 我的对象未定义 (ngoninit) 但在其他函数中我可以获得值。

我的问题是为什么以及如何才能在 ngoninit 中获取我的对象。

谢谢

我在邮递员上正确检索了我的回复其他函数也检索

服务：

getById(id:string):Observable<Grower>{
   return this.http.get<Grower>(`${environment.apiUrl}/growers/${id}`);
}

查看模型：

export class GrowerDetails {

    adress:string;
    zip:string;
    city:string;
}

组件：

  growerService:GrowerService;

  detailsProfil: GrowerDetails;

  constructor(private authenticationService: AuthenticationService, growerService:GrowerService,
    private formBuilder:FormBuilder) { 
      this.growerService = growerService;
   }

  ngOnInit() {
    this.detailsProfil = new GrowerDetails();

    this.growerService.getById(this.decoded.nameid).subscribe(
      (data:Grower) => this.detailsProfil = {
            adress: data.adress,
            city: data.city,
            zip : data.zip

      },
      error => console.log(error) 
    );
console.log(this.detailsProfil); // undefinned

onSubmit(){
    console.log(this.detailsProfil); // ok
 }

邮递员：

{
    "lat": 0,
    "long": 0,
    "description": "test",
    "adress": "test",
    "zip": "test",
    "city": "test"
}

Answer 1

我们可以在订阅内部获得 detailsProfil 的值，但不能在订阅外部获得。因为 getById() 是一个 async 调用所以不会等待订阅完成执行。

像下面这样做一些改变，

 constructor(private authenticationService: AuthenticationService, growerService:GrowerService,
    private formBuilder:FormBuilder) { 
      //  this.growerService = growerService;  <- this line not required
   }

  ngOnInit() {
    this.detailsProfil = new GrowerDetails();

    this.growerService.getById(this.decoded.nameid).subscribe((data) => {
       console.log(data);            
       this.detailsProfil.adress = data.adress;
       this.details.city = data.city;
       this.details.zip = data.zip;
     },
      error => console.log(error));
     console.log(this.detailsProfil); // you will get detailsProfil Object
  }

快乐编码..:)

Answer 2

未定义，因为您还没有数据。

     ngOnInit() {
        this.detailsProfil = new GrowerDetails();

        this.growerService.getById(this.decoded.nameid).subscribe(
          (data:Grower) => {
             this.detailsProfil = {adress: data.adress,city: data.city,zip : data.zip };

             console.log(this.detailsProfil); // you can access here because you got it now.
          },
          error => console.log(error) 
        );

    console.log(this.detailsProfil); // you can't access here. it's still undefined 
  }

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