Angular 中的错误 - 基于 firebase 的聊天应用程序

error in Angular - firebase based chat Application

我正在使用 Angular 6 和 Firebase 创建一个聊天应用程序,但我遇到了以下错误:

错误 1 ​​-

我在从 angularfire2/database

导入 FirebaseListObservable 时遇到错误
import { AngularFireDatabase, FirebaseListObservable} from 'angularfire2/database';

[ts] Module '"/Users/user/Projects/A4/chat-app/node_modules/angularfire2/database/index"' has no exported member 'FirebaseListObservable'.

错误 - 2

[ts] Argument of type '{ query: { limitToLast: number; orderByKey: boolean; }; }' is not assignable to parameter of type 'QueryFn'. Object literal may only specify known properties, and 'query' does not exist in type 'QueryFn'.

getMessages(): FirebaseListObservable<ChatMessage[]> {

return this.db.list('messages', {
  query: {
    limitToLast: 25,
    orderByKey: true
  }
});

恰克Angular2 fire has no exported member 'FirebaseListObservable'

您需要更改应用组件中的依赖项,如下所示:

`import {AngularFireDatabase , FirebaseListObservable} from "angularfire2/database";`

`import { AngularFireDatabase, FirebaseListObservable } from 'angularfire2/database-deprecated';`

它会起作用。