GMap3 Wicket Component

This component (isis-wicket-gmap3) allows an entity or collection of entities to be rendered within a map (using google’s gmap3 API).


The module’s functionality can be explored by running the quickstart with example usage using the

Note that the isis.viewer.wicket.gmap3.apiKey must be set to a valid value; this is most easily done using a system property.

A home page is displayed when the app is run:

010 install fixtures

Parented collection as gmap

The todo item’s collection contains a list of Locatable entities (also todo items); this is indicated through a button to switch the view:

020 gmap button available on parented collection

Clicking the button shows the same entities on a gmap3:

030 view collection in gmap3 next update location

Update location using service

The previous screenshot shows the todo item also provides an "update location" action:

public Gmap3WicketToDoItem updateLocation(
        final String address) {
    final Location location = this.locationLookupService.lookup(address);
    return this;

When invoked:

040 update location invoke

... it updates the location:

050 location updated

Standalone location as gmap

Invoking an action that returns a list of Locatable entities also results in the button to view in a gmap3:

070 gmap button available on standalone collection

... which then renders the items in a map. Note the tooltips:

080 view collection in gmap3

Click through

Clicking on a map marker drills down to the entity:

090 click through to entity

API & Usage

Rendering objects on a map

Make your entity implement org.isisaddons.wicket.gmap3.applib.Locatable, such that it provides a Location property of type org.isisaddons.wicket.gmap3.applib.Location.

This property will need to be annotated as @javax.jdo.annotations.Persistent.

For example:

import org.isisaddons.wicket.gmap3.cpt.applib.Locatable;
import org.isisaddons.wicket.gmap3.cpt.applib.Location;

public class ToDoItem implements Locatable {
    private Location location;

    @MemberOrder(name="Detail", sequence = "10")
    public Location getLocation() {
        return location;
    public void setLocation(Location location) {
        this.location = location;

You should then find that any collections of entities that have Locatable properties (either returned from an action, or as a parented collection) will be rendered in a map.


By injecting the provided LocationLookupService domain service, you can write an action to lookup Locations.

For example:

public void lookupLocation(
        final String description) {

To use this the LocationLookupService needs to be registered; see below.

Alternatively, the Location can also be specified directly as a string. The format is mmm.mmm;nnn.nnn, where mmm.mmm is the latitude, and nnn.nnn is the longitude


Sometimes the domain object that implements Locatable will be a supporting object such as an Address, belonging to a Customer, say. When the location marker is clicked in the map, we would rather that the UI opens up the Customer rather than the associated Address (in other words, saving a click).

This requirement is supported by providing an implementation of the LocationDereferencingService:

public interface LocationDereferencingService {
        Object dereference(final Object locatable);

for example, one might have:

public class LocationDereferencingServiceForAddress implements LocationDereferencingService {
        public Object dereference(final Object locatable) {
                if (!(locatable instanceof Address)) {
                        return null;
                final Address address = (Address) locatable;
                return address.getCustomer();

Note that there can be multiple implementations of this service; the component will check all that are available. The order in which they are checked depends upon the @DomainServiceLayout(menuOrder=…​) attribute.

How to configure/use


Add the component to your project’s dom module’s pom.xml:


Check for later releases by searching Maven Central Repo.

For instructions on how to use the latest -SNAPSHOT, see the contributors guide.


In the AppManifest, update its getModules() method, eg:

public List<Class<?>> getModules() {
    return Arrays.asList(

This will register the LocationLookupService.

Configuration Properties

gmap3 API Key

In order to use the component an API key is required. See the google documentation for instructions as to how to do this; a free key (with quite generous daily limits) can be used.

Configure the key in WEB-INF/ (or WEB-INF/


Known issues

None known at this time.


Maven can report modules dependencies using:

mvn dependency:list -o -pl modules/wkt/gmap3/impl -D excludeTransitive=true

which, excluding Apache Isis itself, returns these compile/runtime dependencies:


For further details on 3rd-party dependencies, see:

In addition to Apache Isis, this component depends on: