Ionic 2 Angular 2 Google Maps Adding multiple markers from database coordinates

Question

I am trying to place multiple markers on a map in my native Ionic 2 app.

    //Connecting to locations database
    this.db.connect();
    let locations = this.db.collection('locations');

    //Retrieving all the locations of users from database
    locations.fetch().subscribe(msg => console.log(msg));

    //loop through all the locations, adding markers at each position
    for (let i = 0; i < 10; i++) {

        let pin = locations[i];
        let location: any;

        let marker = new google.maps.Marker({
                map: this.map,
                animation: google.maps.Animation.DROP,
                position : {"lat": 2433, "lng": 234}
        });

        //Content displayed in window on Map
        let content = 
        //User profile information
        '<h3>Name: </h3>' + this.user.details.name + 
        '<h3>Email: </h3>' + this.user.details.email + 
        '<h3>Image: </h3>' + '<img src='+this.user.details.image+'>' +
        '<button id="sendRequest()" (click)>Request Walk</button>';

        this.addInfoWindow(marker, content);
    }
    //end of locations loop

At the moment the long and lat figures are made up coordinates. I have a locations database containing user email, lat and lng data. I have this data in my console log: console log displaying locations array

I am wondering how I can access this data and use it to plot multiple different markers on my map.

Paolo Stefan · Accepted Answer · 2017-03-13 16:12:47Z

Assuming that the msg variable is the one you dumped in the pasted picture, you should loop over the records once you get them all, that is, for instance:

locations.fetch().subscribe(msg:Array => {
  var bounds = new google.maps.LatLngBounds();

  for (let record of msg) {    
    var marker = new google.maps.Marker({
      map: this.map,
      animation: google.maps.Animation.DROP,
      position: { lat: record.lat, lng: record.long }
      __infowindow: new google.maps.InfoWindow({
        content: '<h3>Email: </h3>' + record.email;
      })
    });

    marker.addListener('click', ()=>{
      // this- here -is the marker
      // this.map means marker.map, we are lucky it's the same as ...Page.map
      this.__infowindow.open(this.map, this);
    });
    bounds.extend(marker.getPosition());
  }
  this.map.fitBounds(bounds);
});

The tricky part is the __infowindow field of the object passed to the Marker constructor. It's a workaround to avoid JS errors - i.e. if we used let infowindow =..., the variable would be destroyed after the for loop; if we used a var infowindow = ..., it would be set to the last infowindow created in the for loop.

I haven't tested this exact code, but something really similar, and it works.

As a bonus, I've added these instructions:

var bounds = new google.maps.LatLngBounds();
...
bounds.extend(marker.getPosition());
...
this.map.fitBounds(bounds);

so that once you added all the markers, the map will autoresize to fit them all ;-).

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