I can't get the data from firebase in feed component.

[isitme]

I'm currently using angular 6

i did all the same in feed.component.ts

import { Component, OnInit, OnChanges } from '@angular/core';
import { ChatService } from '../services/chat.service';
import { Observable } from 'rxjs';
import { chatMessegeModel } from '../models/chat-message.model';
import { FirebaseListObservable } from 'angularfire2/database';

@component({
selector: 'app-feed',
templateUrl: './feed.component.html',
styleUrls: ['./feed.component.css']
})
export class FeedComponent implements OnInit, OnChanges {
feed: FirebaseListObservable<chatMessegeModel[]>;

constructor(private chat: ChatService) { }

ngOnInit() {
this.feed = this.chat.getMessages();
}

ngOnChanges() {
this.feed = this.chat.getMessages();
}

}
and the Template:

*ngFor="let message of feed | async"
<app-message [chatMessage]=message >

But the console show me this Error:

ERROR TypeError: rxjs_operators__WEBPACK_IMPORTED_MODULE_4__.switchMap.call(...).subscribe is not a function
at FirebaseListObservable._subscribe (firebase_list_factory.js:75)
at FirebaseListObservable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable._trySubscribe (Observable.js:42)
at FirebaseListObservable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe (Observable.js:28)
at ObservableStrategy.push../node_modules/@angular/common/fesm5/common.js.ObservableStrategy.createSubscription (common.js:4498)
at AsyncPipe.push../node_modules/@angular/common/fesm5/common.js.AsyncPipe._subscribe (common.js:4578)
at AsyncPipe.push../node_modules/@angular/common/fesm5/common.js.AsyncPipe.transform (common.js:4559)
at Object.eval [as updateDirectives] (FeedComponent.html:1)
at Object.debugUpdateDirectives [as updateDirectives] (core.js:11061)
at checkAndUpdateView (core.js:10458)
at callViewAction (core.js:10699

[kranthi1996]

this.chatservice.getMessages().valueChanges().subscribe(data => {
this.messagesData = data;
})

[al-freezy]

this.chatservice.getMessages().valueChanges().subscribe(data => { this.messagesData = data; })

And how do you write it in the html template?