Ionic 4/Angular - Geolocation Plugin, Google Maps and Places API [Part 2]

On the previous part we have added a Google Map to our Ionic 4 application and used the Cordova Geolocation plugin and its Ionic native wrapper to get the current user position.

Check out the first part:

Ionic 4 - Geolocation Plugin, Google Maps and Places API

On this part we are going to continue building our nearby restaurants mobile app so let's get started.

First of all, you need to change the script tag for including the Google Maps JavaScript SDK in the src/index.html file to enable the Places API:

<script src="http://maps.google.com/maps/api/js?key=YOUR_API_KEY&libraries=places"></script>

Next open the src/pages/home/home.scss file and add these styles:

page-home {
    .scroll {
        height: 100%
    }

    #map {
        width: 100%;
        height: 40%;
    }
} 

The Google map will take only 40% of height.

Next, open the src/pages/home/home.html file and change it accordingly:

<ion-header>
<ion-navbar>
    <ion-title>
    Nearby Me Restaurants
    </ion-title>
</ion-navbar>
</ion-header>

<ion-content padding>

<div #map id="map"></div> 

<div style="width : 100% ;height: 60%">
    <ion-list>
    <ion-item *ngFor="let place of places">
        <p></p>
    </ion-item>
    </ion-list>
</div>

</ion-content>

Now, in the src/pages/home/home.ts file, add a member variables of type Array to hold the nearby places:

declare var google;

@Component({
selector: 'page-home',
templateUrl: 'home.html'
})
export class HomePage {
options : GeolocationOptions;
currentPos : Geoposition;
places : Array<any> ; 

Next, add a getRestaurants() method to get the list of the nearby restaurants:

getRestaurants(latLng)
{
    var service = new google.maps.places.PlacesService(this.map);
    let request = {
        location : latLng,
        radius : 8047 ,
        types: ["restaurant"]
    };
    return new Promise((resolve,reject)=>{
        service.nearbySearch(request,function(results,status){
            if(status === google.maps.places.PlacesServiceStatus.OK)
            {
                resolve(results);    
            }else
            {
                reject(status);
            }

        }); 
    });

}

This method returns a Promise which resolves with the list of restaurants or if there is an error it will be rejected with the status code.

We have wrapped the service.nearbySearch() method, which uses callbacks, in a Promise to play nice with the Angular change detection.

Also add a createMarker() method:

createMarker(place)
{
    let marker = new google.maps.Marker({
    map: this.map,
    animation: google.maps.Animation.DROP,
    position: place.geometry.location
    });   
}   

This method creates a marker from a place. It's called for every place returned by the nearbySearch() method.

Finally update the addMap() method to invoke the previous methods:

addMap(lat,long){

    let latLng = new google.maps.LatLng(lat, long);

    let mapOptions = {
    center: latLng,
    zoom: 15,
    mapTypeId: google.maps.MapTypeId.ROADMAP
    }

    this.map = new google.maps.Map(this.mapElement.nativeElement, mapOptions);

    this.getRestaurants(latLng).then((results : Array<any>)=>{
        this.places = results;
        for(let i = 0 ;i < results.length ; i++)
        {
            this.createMarker(results[i]);
        }
    },(status)=>console.log(status));

    this.addMarker();

}

The places variable holds the list of the nearby restaurants which are then displayed using <ion-list> on the view.

Conclusion

That is it! You have now created a nearby app with Ionic 4/Angular which gets the current user location using the Cordova Geolocation plugin and Ionic Native then uses the Google Places API to search for the nearby restaurants and display them in a Google Map.


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