更新.snapshotChanges()代码以使用angularfire2 5.0.0 rc-8，firebase 5.0.2

Question

我已经成功地更新了angularfire 5.0.0.rc8和firebase 5.0.2，没有错误模块。我想我要做的最后一件事就是修改这个代码来检索所有数据。

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import { IonicPage } from 'ionic-angular/navigation/ionic-page';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';
import { Note } from '../../model/note/note.model';
import { NoteListService } from '../../services/note-list.service';

@IonicPage()
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {

  noteList: Observable<Note[]>

  constructor(public navCtrl: NavController, private noteListService: NoteListService) {
    this.noteList = this.noteListService.getNoteList()
      .snapshotChanges()
      .map(
        changes => {
          return changes.map(c => ({
            key: c.payload.key, ...c.payload.val()
          }))
        });
  }
}

noteListService文件..。

import { Injectable } from '@angular/core';
import { AngularFireDatabase } from 'angularfire2/database';
import { Note } from '../model/note/note.model';

@Injectable()
export class NoteListService {

    private noteListRef = this.db.list<Note>('note-list');

    constructor(private db: AngularFireDatabase) { }

    getNoteList() {
        return this.noteListRef;
    }

    addNote(note: Note) {
        return this.noteListRef.push(note);
    }

    updateNote(note: Note) {
        return this.noteListRef.update(note.key, note);
    }

    removeNote(note: Note) {
        return this.noteListRef.remove(note.key);
    }
}

帮助更改此代码，该代码将与我的新版本angularfire 5.0.0 rc 8和firebase 5.0.2兼容

这是一个新的错误后，我的一半的代码正在工作。插入零件。但我还是无法质疑

运行时错误隐藏(承诺)：this.noteListService.getNoteList(...).snapshotChanges(...).map不是TypeError A function TypeError: TypeError不是在createClass (http://localhost:8100/build/vendor.js:10575:20) at createDirectiveInstance (http://localhost:8100/build/vendor.js:10458:20) at createViewNodes (http://localhost:8100/build/vendor.js:11680:36) at createRootView (http://localhost:8100/build/vendor.js:11594:5) at callWithDebugContext (http://localhost:8100/build/vendor.js:12629:25) at Object.debugCreateRootView as createRootView at ComponentFactory_.create (http://localhost:8100/build/vendor.js:12629:25) at ComponentFactory_.create() at (http://localhost:8100/build/vendor.js:49286:44 )处的新HomePage (http://localhost:8100/build/0.js:86:14)的函数)堆栈错误: Uncaught (为了承诺)：this.noteListService.getNoteList(...).snapshotChanges(...).map不是一个函数

Answer 1

新版本angularfire v5.0.0-rc.9每样东西都很好。

这是从firebase检索数据的代码。

import { Component, Injectable } from '@angular/core';
/*import { NavController } from 'ionic-angular';*/
import { IonicPage } from 'ionic-angular/navigation/ionic-page';
import { AngularFireDatabase, AngularFireList } from 'angularfire2/database';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';
import { Note } from '../../model/note/note.model';

@Injectable()
@IonicPage()
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {
  itemsRef: AngularFireList<any>;
  items: Observable<Note[]>;
  constructor(db: AngularFireDatabase) {
    this.itemsRef = db.list('note-list');
    this.items = this.itemsRef.snapshotChanges().pipe(
       map(changes =>
         changes.map(c => ({ key: c.payload.key, ...c.payload.val() }))
      )
    );
  }
}

https://github.com/bnayak0225/Biswajit-Note-Ionic-Firebase-angularfire2-5.0.0-rc-9

Answer 2

您还没有正确地从rxjs导入map操作符，而且在rxjs 6中还需要使用pipe。

...
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@IonicPage()
@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {

  noteList: Observable<Note[]>

  constructor(public navCtrl: NavController, private noteListService: NoteListService) {
    this.noteList = this.noteListService.getNoteList()
      .snapshotChanges()
      .pipe(
        map(changes => 
          changes.map(c => ({
            key: c.payload.key, ...c.payload.val()
          }))
        })
      );
  }
}