变量在订阅（）方法Angular 2之外未定义

Question

我正在处理 angular 2 并且在 subscribe() 函数之外的变量出现未定义错误。employee 变量 id undefined 在 subscribe() 函数之外。请帮助我。谢谢。下面是代码

export class DetailsComponent implements OnInit {
  employee;

  constructor(private _location:Location, private _empService:EmpService, private route:ActivatedRoute) { }
  ngOnInit() {
      //let params:any = this.route.snapshot.params;

      this.editEmployee(6); //I have tried to pass static value
      console.log(this.employee); //Here this is undefined  
  }
  backClicked() {
        this._location.back();
    }

   editEmployee(id) {
    this._empService.getEmployee(id).subscribe((employee)=> {
       this.employee = employee[0];
       console.log(employee[0]); //This have below output in console
       //{id: "6", emp_name: "Mohit", emp_email: "mohit@ommzi.com", emp_phone: "9800000", emp_status: "y"}
    })
  }
}

Answer 1

因为您使用的是 Observables，所以在设置员工之前会调用 console.log(this.employee)。我会在 editEmployee 中建议您返回一个 Promise 并使用：

editEmployee(id) {
    return new Promise((resolve) => {
        this._empService.getEmployee(id).subscribe((employee)=> {
            this.employee = employee[0];
            console.log(employee[0]);
            resolve();
        });
    });
}

this.editEmployee(6).then(()=> {
    console.log(this.employee);
}

请注意，这不是最好和最漂亮的解决方案，但如果你想保持你的代码保持这种风格，我会这样做。