angular2firebase snapshotchanges（）订阅中的错误

Question

尝试使用snapshotChanges（）从firebase获取数据时出现changes.forEach错误，但如果我使用valuechanges（），它会正常工作。我不确定我做错了所以请帮忙

import { Injectable } from '@angular/core';
import { AngularFirestore, AngularFirestoreCollection, 
AngularFirestoreDocument } from "angularfire2/firestore";
import { BehaviorSubject } from "rxjs/BehaviorSubject";
import { of } from "rxjs/Observable/of";
import {Observable} from 'rxjs';
import 'rxjs/add/operator/map';
import { Employee } from "../models/employee";`

@Injectable()
export class EmployeeService {
employees: Observable<Employee[]>;
employeeCollection: AngularFirestoreCollection;`

constructor( public db: AngularFirestore ) {
db.firestore.settings({ timestampsInSnapshots: true });
this.employeeCollection = this.db.collection('employee');
this.employees = this.employeeCollection.snapshotChanges().map(changes => {
 return changes.map(a => {
   const data = a.payload.doc.data() as Employee;
    data.id = a.payload.doc.id;
    return data;
    });
 });
}

getEmployees(){
  return this.employees;
}

这是我的组件

import { Component, OnInit } from '@angular/core';
import { EmployeeService } from "../../services/employee.service";
import { Employee } from "../../models/employee";

@component({
  selector: 'app-employees',
  templateUrl: './employees.component.html',
  styleUrls: ['./employees.component.css']
  })

export class EmployeesComponent implements OnInit {
employees: Employee[];
constructor(
   private employeeService: EmployeeService
) { }`

ngOnInit() {
 this.employeeService.getEmployees().subscribe(employees => {
 this.employees = employees;
});`

然后我在Chrome控制台上收到此错误

Answer 1

我有同样的问题，我解决了它降级到以前的版本。我现在使用firebase 4.12.1和angularfire2 5.0.0-rc.6。我实际上降级到以前版本的角度和RxJs以及新版本引入了重大变化，我将不得不使用rxjs-compat包使它工作......这是一个烂摊子。我现在将使用这些版本，直到所有第三方库都添加对新版rxjs的支持。 这是我的package.json：

{
  "name": "support-portal",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^5.0.0",
    "@angular/common": "^5.0.0",
    "@angular/compiler": "^5.0.0",
    "@angular/core": "^5.0.0",
    "@angular/forms": "^5.0.0",
    "@angular/http": "^5.0.0",
    "@angular/platform-browser": "^5.0.0",
    "@angular/platform-browser-dynamic": "^5.0.0",
    "@angular/router": "^5.0.0",
    "angularfire2": "^5.0.0-rc.6",
    "core-js": "^2.4.1",
    "firebase": "^4.12.1",
    "rxjs": "^5.5.2",
    "rxjs-compat": "^6.1.0",
    "zone.js": "^0.8.14"
  },
  "devDependencies": {
    "@angular/compiler-cli": "^5.0.0",
    "@angular-devkit/build-angular": "~0.6.0",
    "typescript": "~2.4.2",
    "@angular/cli": "~6.0.0",
    "@angular/language-service": "^6.0.0",
    "@types/jasmine": "~2.8.6",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.2.1",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~1.7.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~1.4.2",
    "karma-jasmine": "~1.1.1",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.3.0",
    "ts-node": "~5.0.1",
    "tslint": "~5.9.1"
  }
}

我希望这可以帮助您启动并运行，但这是一个临时解决方案，我们都应该能够使用最新版本。