1.5.5. Using Events

Let us consider the use of events. We will add handling of a graph item click to the screen created in Creating Chart. Open the screen controller in the IDE and inject the chart:

@Inject
private SerialChart serialChart;

Then add a listener at the bottom of the init(Map<String, Object> params) method. When a chart receives data from DataProvider, the getDataItemNN() method should be used to get the item clicked. In this example, the SerialChart component is bound to the datasource, so another method should be used: getEntityNN():

serialChart.addGraphItemClickListener(event -> {
        CountryGrowth countryGrowth = (CountryGrowth) event.getEntityNN();
        String message = String.format("GDP grow in %s (%s): %.1f%%",
        countryGrowth.getCountry(),
        event.getGraphId().substring(5),
        "graph2014".equals(event.getGraphId()) ? countryGrowth.getYear2014() : countryGrowth.getYear2015());
        showNotification(message, NotificationType.HUMANIZED_HTML);
});

To see the results, rebuild the project using Run → Restart application server and log in to the system. Open the screen and click one of the columns.

chart with event
Figure 3. Chart that handles graph item click event