Logging Image Tag by Event Handler

[Vodjakxa]

I have to make an event handler that fires and prints logs whenever tags are assigned to images on the Dam. Finally I have to print the list of tags used on the images with the logs

[konstantyn_diachenko · Accepted solution]

Hi @Vodjakxa ,

I found that OOTB there is a Dam Event. 

So, you can build your logic around this event.

import com.day.cq.dam.api.DamEvent;
import lombok.extern.slf4j.Slf4j;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventConstants;
import org.osgi.service.event.EventHandler;
@Slf4j
@Component(
        service = EventHandler.class,
        property = {
                EventConstants.EVENT_TOPIC + "=" + DamEvent.EVENT_TOPIC
        },
        immediate = true
)
public class DamTagAssignEventListener implements EventHandler {
    @Override
    public void handleEvent(Event event) {
        log.info(event.toString());
        DamEvent damEvent = DamEvent.fromEvent(event);
        if (damEvent == null) {
            return;
        }
        if (DamEvent.Type.METADATA_UPDATED != damEvent.getType()) {
            return;
        }
        String additionalInfo = damEvent.getAdditionalInfo();
        if (additionalInfo == null || !additionalInfo.contains("jcr:content/metadata/cq:tags")) {
            return;
        }
        String tags = additionalInfo.substring(additionalInfo.indexOf("=") + 1);
        log.info("{} : {}", damEvent.getAssetPath(), tags);
    }
}

However, I noticed that additionalInfo always contains only 1st tag even if you assigned 2+ tags. Most likely you need to cache previous state of asset tag by extra call before saving of asset.

In addition, processing of Event Handler should not take more than 5 sec, otherwise it will be black-listed. If you have complex calculation, you need to start Sling Jobs immediately in Event Handler to outsource handing of event in another thread.

Best regards,

Kostiantyn Diachenko. 

[PavanGaddam]

@Vodjakxa Are you trying to do this in AEM Cloud Service? If so, using AEM Eventing is the recommended approach. Refer to [0], [1] for more details. You need to use "Asset Metadata Updated" event for capturing the tags updated event.

[0] - https://experienceleague.adobe.com/en/docs/experience-manager-learn/cloud-service/aem-eventing/overv...

[1] - https://developer.adobe.com/experience-cloud/experience-manager-apis/guides/events/#enable-aem-event...