使用 Firebase Cloud Firestore、Ionic Framework、Angular 获取服务器时间戳的最佳方法是什么？

Question

I am working in the project which truly based on clock time. It has a functionality to work same on desktop and mobile app ( Android/iOS ) using Ionic Framework .

If some of the user change the mobile time or system time, our complete app will get change the results.

So somewhere i found the some answer which shows that get the server time from web Server programming language.

But i am not using any web framework language.

    triggerNextTicket(){
     Observable.interval(1000).map((x) => {
    let date = +new Date().getTime() ;
    if( (this.nextTicket.ticket_live_at.seconds * 1000) < date){
      this.ngOnInit();
    }
    if((this.ticketData.ticket_live_at.seconds * 1000) < date){
      this.ngOnInit();
    }

Actuaally, the main problem in this code is, if the Mobile system time changed by the user manually, then our app shows the past data .

let date = +new Date().getTime() 

in any case my date variable will be fresh, if the user change their system time or in any case.

Thanks

Answer 1

Here a simple way to tell Firestore to write the server-side timestamp to a document:

var ref = db.collection("54201787").doc("time");
ref.set({ timestamp: firebase.firestore.FieldValue.serverTimestamp() });

And here's how you read that value back into your client:

ref.onSnapshot(function(snapshot) {
  var timestamp = snapshot.data().timestamp;
  console.log(timestamp.toString());
})

In this last snippet the timestamp variable is a Date object , so you can access all its other methods and properties too.

For a working sample of this code, see: https://jsbin.com/burimih/edit?html,js,console

Answer 2

You should use firebase.firestore.FieldValue.serverTimestamp() while creating/updating a document as well as validate the same in security rules.

Example:

To set serverTime in a document

      db.collection("fooBar")
      .doc()
      .set({
        createdAt: firebase.firestore.FieldValue.serverTimestamp(),
        createdBy: this.props.user.uid,
        foo: 'bar',
      })
      .then(() => console.log("Success"))
      .catch(console.error);

Security Rule

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read;
      allow write: if request.resource.data.createdBy == request.auth.uid && request.time == request.resource.data.createdAt
    }
  }
}

This way I can verify there are no client manipulated values in my database.

Also, notice how I validate user uid against request.auth.uid