angularfire2

问题 I have project that I need to display a leaderboard of the top 20, and if the user not in the leaderboard they will appear in the 21st place with their current ranking. Is there efficient way to this? I am using Cloud Firestore as a database. I believe it was mistake to choose it instead of MongoDB but I am in the middle of the project so I must do it with Cloud Firestore. The app will be use by 30K users. Is there any way to do it without getting all the 30k users? this.authProvider.afs

问题 I am trying to find all the objects that are between two dates. the code look like below getPendingOrders(dateFrom:number, dateTo:number){ console.log('start of getPendingOrders with dateFrom:' + dateFrom + " dateTo:" + dateTo) return new Promise((resolve, reject) => { this.db.list('orders', ref => ref.orderByChild("order/_date").startAt(dateFrom).endAt(dateTo) ).snapshotChanges().subscribe( res => { console.log('response:' + JSON.stringify(res)) resolve(res) }, err => { console.log(err)

问题 I am creating Ionic app with database on Firebase,so I have something like this in Firebase, and I am using angularfire2 to get the data and I have no problem on getting paises but I have tried getting the list of jugadores but I get nothing. This is my .ts export class HomePage { paises: Observable<any[]> constructor(public navCtrl: NavController, db: AngularFireDatabase) { this.paises = db.list('paises').valueChanges(); } } and this is my .html <ion-content *ngFor="let pais of paises |

问题 Is this a good practice to save in the database and reuse the url returned by angularfire2's getDownloadURL() rather than executing getDownloadURL() every time I need to display an image from Firebase Storage? If I use getDownloadURL() in my component, images are reloaded every time I access the component. I would like to avoid that. If I save the url in my database after the image was uploaded and then use this url every time I need to display the image this solves the problem. However,

问题 I'm creating a chat app in Angular 4 which stores and reads messages in and from the Firebase database. I've written a query to retrieve only the latest 10 messages of that specific conversation. this.messages = this.db.list('messages/' + conversationId, { query: { limitToLast: 10 } }); db: AngularFireDatabase, messages: FirebaseListObservable Now I want to retrieve the 10 older messages when somene presses the 'more' button (or scrolls to the top) and I'm having difficulties writing a query

问题 If I try to use RxJS operators like .take, .skip, etc. on FireBaseListObservable, I get "take is not a function" error: import {Component} from '@angular/core'; import {AngularFire, FirebaseListObservable} from 'angularfire2'; import {Observable} from 'rxjs'; export class AppComponent { items: FirebaseListObservable<any>; constructor(public af: AngularFire) { // this works Observable.interval(1000).take(5).subscribe(x => console.log(x)); this.items = af.database.list('/items'); // this does

问题 i've got a firebase database. a node called /config// which holds userspecific data. i now want to add a subtree to the userdata with a list of cars, like /config//cars/: "config" : { "NE5AwHcxKofMPKRCAvny5Re4MtG3" : { "geburtstag" : "2017-06-04", "nachname" : Mueller", "cars" : { "-Krr2-DC1uoqCvgVJhFL" : { "name" : "Ford Mustang" }, "-Krue4_5kJQhis-3Qg1X" : { "name" : "Toyota Supra" } } } i created a observable binding to /config/ this.$ref = this.database.object('/config/' + uid); this.data

问题 I am working on Angular 4 project. Here I want to update the form data using firebase key I have pass the data through component.ts as follow this.service.editEnquiry(this.data); I called editEnquiry() of service. the editEnquiry() is given as follows editEnquiry(data) { console.log(data); console.log(data.key); this.af.list(`/enquirydata/`+key).update(data); } I am getting the data in editEnquiry() but its not updating the record in firebase. Its giving me error like this Supplied parameters

问题 I found some tutorials about offline mode firebase for Ionic 2 but still I don't know how can I enable this thing in my application. So, Is firebase realy support offline mode? If yes, can I store all recieved data and run the functions in offline mode ? 回答1: There is no official support yet from firebase.But you can do that using angularfire2-offline library. A simple wrapper for AngularFire2 to read and write to Firebase while offline, even after a complete refresh. Here is a great article

问题 I need to query comments and request only user that listed in the comment by userId. My database structure in Firebase realtime db: { "comments" : { "c_id1" : { "commentId" : "c_id1", "commentText" : "text", "userId" : "u_id1" }, "c_id2" : { "commentId" : "c_id2", "commentText" : "text", "userId" : "u_id3" }, }, "users" : { "u_id1" : { "userId" : "u_id1", "userName" : "name1", }, "u_id1" : { "userId" : "u_id2", "userName" : "name2", }, "u_id1" : { "userId" : "u_id3", "userName" : "name3", } }