错误错误：未捕获（在承诺中）：TypeError：无法设置未定义的属性“empolyee”

Question

我希望通过employee从employee.serves.ts文件获取员工对象到employee-info.component.ts文件，以便在HTML中查看该对象的数据。

主要问题是如何从firestore获取id的对象？ （只有一个对象不是集合中的所有id对象）

employee.serves.ts文件中的doc.data（）给了我想要的对象，但是如何将这些数据发送到employee-info.component.ts以便在HTML中查看它。

employee.serves.ts文件

import { Injectable } from '@angular/core';
import { AngularFirestore, AngularFirestoreCollection, AngularFirestoreDocument } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Observable';
import { Employee } from '../models/Employee';

@Injectable()
export class EmployeeService {
    employeesCollection: AngularFirestoreCollection<Employee>;

    empolyee: Observable<Employee>;

    constructor(public afs: AngularFirestore) {
        this.employeesCollection = this.afs.collection('employees');
    }

    getEmployee(id){
        this.employeesCollection.doc(id).ref.get().then(function(doc) {
            this.empolyee = doc.data();
        });
        return this.empolyee;
    }
}

employee-info.component.ts文件

import { Component, OnInit } from '@angular/core';
import { EmployeeService } from '../../services/employee.service';
import { Employee } from '../../models/Employee';
import { FlashMessagesModule } from 'angular2-flash-messages';
import { Router, ActivatedRoute, Params } from '@angular/router';

@Component({
    selector: 'app-employee-info',
    templateUrl: './employee-info.component.html',
    styleUrls: ['./employee-info.component.css']
})
export class EmployeeInfoComponent implements OnInit {
    id: string;
    employee : Employee;

    hasSalary: boolean = false;
    updateSalary: boolean = false;

    constructor(private employeeServaice: EmployeeService, 
                private router: Router,
                private activateRoute: ActivatedRoute,
                private fmService: FlashMessagesModule ) { 

    }

    ngOnInit() {
        this.id = this.activateRoute.snapshot.params['id'];
        this.employeeServaice.getEmployee(this.id).subscribe(employee => {
            this.employee = employee;
            console.log(this.employee);
        });
    }
}

Answer 1

 getEmployee(id){
        this.employeesCollection.doc(id).ref.get().then(function(doc) {
            this.empolyee = doc.data();
        });
        return this.empolyee;
 }

 // Use Arrow function inside callback 

 getEmployee(id){
        this.employeesCollection.doc(id).ref.get().then((doc) => {
            this.empolyee = doc.data();
        });
        return this.empolyee;
 }