Background Geolocation Plugin: Track location and update database every 5 minutes

Question

I'm currently developing a mobile app using AngularJS / Ionic 3.

I need to track at all time, if my users are within a radius of 100m of a certain geolocation (let's call it "Home Location". I need to know at all time which user is at his home location, and who is not (even when the app is running in background or is closed/ terminated).

I thought to realize this, using the Ionic Native Background-Geolocation plugin and the cordova-plugin-background-geolocation. My plan was, to check the users geolocation every 5 minutes and compare it to the home.

Case 1) If the distance between the two locations is < 100m I know the user is "at home". I would then update the user node in my database (Firebase) to mark the user as isAtHome: true and add a current timestamp.

Case 2) If the user is not within 100m of his home location I would mark him as isAtHome: false and add a current timestamp.

I need to update my database even in case the user didn't move, because I need to know that I received a current signal. Otherwise I don't know if he didn't move or turned off his smartphone, for example.

If I want to know, who of my users is at his home location, I would check the isAtHome-attributes and if they are set to true, I would check the timestamp to be sure that I have up-to-date data and the data was written within the last 15 minutes.

I tried many different things, but I'm not sure how to realize this with the Cordova Background Geolocation Plugin and if it's even possible.

My question is:

Is it possible to check the users geolocation every 5 minutes (even in background / terminated state) and call a function that updates my firebase DB accordingly? As described, I need to receive the location even if the user didn't move within the last 5 minutes.

If it isn't possible: Does anybody have an idea, of how to approach the requirements on another way?

Thank you very much for your help!

Answer 1

As described in the cordova-plugin-background-geolocation says, you can configure an interval in milliseconds for the plugin to get the location, see this example from the plugin github page:

backgroundGeolocation.configure(callbackFn, failureFn, {
    desiredAccuracy: 10,
    stationaryRadius: 20,
    distanceFilter: 30,
    url: 'http://192.168.81.15:3000/locations',
    httpHeaders: { 'X-FOO': 'bar' },
    maxLocations: 1000,
    // Android only section
    locationProvider: backgroundGeolocation.provider.ANDROID_ACTIVITY_PROVIDER,
    interval: 60000, // <-- here
    fastestInterval: 5000,
    activitiesInterval: 10000,
    notificationTitle: 'Background tracking',
    notificationText: 'enabled',
    notificationIconColor: '#FEDD1E',
    notificationIconLarge: 'mappointer_large',
    notificationIconSmall: 'mappointer_small'
});

The case is this interval property works only for Android. I would sugest a workaround like this:

public getLocation: boolean = true; // CREATE A BOOLEAN TO KNOW IF YOU CAN GET LOCATION

backgroundGeolocation.start( // i've never used this plugin, so i'm assuming this is what starts de background watcher
  () => {
    if(getLocation == true){
      this.getLocation = false; // SET TO FALSE SO IT DON'T DO YOUR FUNCTION THE NEXT TIME IT GETS THE LOCATION

      // DO YOUR CODE TO SAVE AND CHECK YOUR DATA
      // IT'S BETTER IF YOU USE A PROMISE, ASYNC/AWAIT FOR THE SAVING CODE
      yourSavingCodeFunction().then(() => {
        setTimeout(()=>{
          // AFTER 5 MINUTES, SET THE GETLOCATION TO TRUE SO IT CAN DO YOUR FUNCTION AGAIN
          this.getLocation = true;
        }, 500000);
      });
    }
  },
  (error) => {
    // Tracking has not started because of error
    // you should adjust your app UI for example change switch element to indicate
    // that service is not running
  }
);

If you haven't thought about your cases 1 and 2 we can work on this too. Hope this helps or can give you some ideas :D