Odtnhj

i am quite new to observables and firebase. I want to retrieve changes from my firestore to my angular app when a change happens. For example i want to send an alert from my component when field isOnline from my user document changes from false to true(this will be done by the admin). How can i go about it?

From the example The Unreal gave ;

constructor(db: AngularFirestore) {
this.user = db.collection('users/1').valueChanges().subscribe((userData) => 
// put your logic here
console.log(userData);;

If userdata has a field of let's say isOnline which is false from the onset. If an admin changes it to true i want to take that change from that service and alert my component or in this instance, my ionic page of that change and display an alert in my html file.

if in my ts file i have a public variable of let's say isOnline which i initialized to false. If it is true then display an alrt controller in my html file. How do i go about it?

If you are using angularfire2, you can simply use the valueChanges() method of an AngularFireList<T> instance.

For example:

constructor(db: AngularFirestore) {
 this.user = db.collection('users/1').valueChanges().subscribe((userData) => 
 // put your logic here
 console.log(userData);;
 

userDatacontains latest information in your users/1 document.

For more examples & basic usage details, please check the repository page.