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Start a local Quickstart author instance of AEM running at .

Open a terminal window and clone the WKND code base using Git:

$ git clone git@github.com:adobe/aem-guides-wknd.git

Deploy the WKND code base to a local instance of AEM:

$ cd aem-guides-wknd
$ mvn clean install -PautoInstallSinglePackage

Open a new browser window and login to AEM. Open a Magazine page like: .

You should see an example of the Byline component that has been added to the page as part of an Experience Fragment. You can view the Experience Fragment at

Open your developer tools and enter the following command in the Console:

window.adobeDataLayer.getState();

To see the current state of the data layer on an AEM site inspect the response. You should see information about the page and individual components.

Observe that the Byline component is not listed in the Data Layer.

Open the aem-guides-wknd project in the IDE of your choice. Navigate to the core module.

Open the file Byline.java at core/src/main/java/com/adobe/aem/guides/wknd/core/models/Byline.java.

Add below method to the interface:

public interface Byline {
    ...
    /***
     * Return data about the Byline Component to populate the data layer
     * @return String
     */
    String getData();
}

Open the file BylineImpl.java at core/src/main/java/com/adobe/aem/guides/wknd/core/models/impl/BylineImpl.java. It is the implementation of the Byline interface and is implemented as a Sling Model.

Add the following import statements to the beginning of the file:

import java.util.HashMap;
import java.util.Map;
import org.apache.sling.api.resource.Resource;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.adobe.cq.wcm.core.components.util.ComponentUtils;

The fasterxml.jackson APIs are used to serialize the data to be exposed as JSON. The ComponentUtils of AEM Core Components are used to check if the data layer is enabled.

Add the unimplemented method getData() to BylineImple.java:

public class BylineImpl implements Byline {
    ...
    @Override
    public String getData() {
        Resource bylineResource = this.request.getResource();
        // Use ComponentUtils to verify if the DataLayer is enabled
        if (ComponentUtils.isDataLayerEnabled(bylineResource)) {

            //Create a map of properties we want to expose
            Map<String, Object> bylineProperties = new HashMap<String,Object>();
            bylineProperties.put("@type", bylineResource.getResourceType());
            bylineProperties.put("name", this.getName());
            bylineProperties.put("occupation", this.getOccupations());
            bylineProperties.put("fileReference", image.getFileReference());

            //Use AEM Core Component utils to get a unique identifier for the Byline component (in case multiple are on the page)
            String bylineComponentID = ComponentUtils.getId(bylineResource, this.currentPage, this.componentContext);

            // Return the bylineProperties as a JSON String with a key of the bylineResource's ID
            try {
                return String.format("{\"%s\":%s}",
                    bylineComponentID,
                    // Use the ObjectMapper to serialize the bylineProperties to a JSON string
                    new ObjectMapper().writeValueAsString(bylineProperties));
            } catch (JsonProcessingException e) {

                LOGGER.error("Unable to generate dataLayer JSON string", e);
            }

        }
        // return null if the Data Layer is not enabled
        return null;
    }
}

In the above method, a new HashMap is used to capture the properties to be exposed as JSON. Notice that existing methods like getName() and getOccupations() are used. The @type represents the unique resource type of the component, it allows a client to easily identify events and/or triggers based on the type of component.

The ObjectMapper is used to serialize the properties and return a JSON string. This JSON string can then be injected into the data layer.

Open a terminal window. Build and deploy just the core module using your Maven skills:

$ cd aem-guides-wknd/core
$ mvn clean install -PautoInstallBundle

Open the aem-guides-wknd project into the IDE. Navigate to the ui.apps module.

Open the file byline.html at ui.apps/src/main/content/jcr_root/apps/wknd/components/byline/byline.html.

Update byline.html to include the data-cmp-data-layer attribute:

  <div data-sly-use.byline="com.adobe.aem.guides.wknd.core.models.Byline"
    data-sly-use.placeholderTemplate="core/wcm/components/commons/v1/templates.html"
    data-sly-test.hasContent="${!byline.empty}"
+   data-cmp-data-layer="${byline.data}"
    class="cmp-byline">
    ...

The value of data-cmp-data-layer has been set to "${byline.data}" where byline is the Sling Model updated earlier. .data is the standard notation for calling a Javaâ„¢ Getter method in HTL of getData() implemented in the previous exercise.

Open a terminal window. Build and deploy just the ui.apps module using your Maven skills:

$ cd aem-guides-wknd/ui.apps
$ mvn clean install -PautoInstallPackage

Return to the browser and reopen the page with a Byline component: .

Open the developer tools and inspect the HTML source of the page for the Byline component:

You should see that the data-cmp-data-layer has been populated with the JSON String from the Sling Model.

Open the browser’s developer tools and enter the following command in the Console:

window.adobeDataLayer.getState();

Navigate beneath the response under component to find the instance of the byline component has been added to the data layer:

You should see an entry like the following:

byline-136073cfcb:
    @type: "wknd/components/byline"
    fileReference: "/content/dam/wknd/en/contributors/stacey-roswells.jpg"
    name: "Stacey Roswells"
    occupation: (3) ["Artist", "Photographer", "Traveler"]
    parentId: "page-30d989b3f8"

Observe that the properties exposed are the same ones added in the HashMap in the Sling Model.

Open the ui.apps module in your IDE

Open the file byline.html at ui.apps/src/main/content/jcr_root/apps/wknd/components/byline/byline.html.

Update byline.html to include the data-cmp-clickable attribute on the Byline’s name element:

  <h2 class="cmp-byline__name"
+    data-cmp-clickable="${byline.data ? true : false}">
     ${byline.name}
  </h2>

Open a new terminal. Build and deploy just the ui.apps module using your Maven skills:

$ cd aem-guides-wknd/ui.apps
$ mvn clean install -PautoInstallPackage

Return to the browser and reopen the page with the Byline component added: .

To test our event, we will manually add some JavaScript using the developer console. See Using the ÃÛ¶¹ÊÓƵ Client Data Layer with AEM Core Components for a video on how to do this.

Open the browser’s developer tools and enter the following method in the Console:

function bylineClickHandler(event) {
    var dataObject = window.adobeDataLayer.getState(event.eventInfo.path);
    if (dataObject != null && dataObject['@type'] === 'wknd/components/byline') {
        console.log("Byline Clicked!");
        console.log("Byline name: " + dataObject['name']);
    }
}

This simple method should handle the click of the Byline component’s name.

Enter the following method in the Console:

window.adobeDataLayer.push(function (dl) {
     dl.addEventListener("cmp:click", bylineClickHandler);
});

The above method pushes an event listener onto the data layer to listen for the cmp:click event and calls the bylineClickHandler.

In the browser, with the Console open, click the name of the author in the Byline component:

You should see the console message Byline Clicked! and the Byline name.

The cmp:click event is the easiest to hook into. For more complex components and to track other behavior it is possible to add custom JavaScript to add and register new events. A great example is the Carousel Component, which triggers a cmp:show event whenever a slide is toggled. See the .

Return to the IDE and navigate to the core module.

Open the file Byline.java at core/src/main/java/com/adobe/aem/guides/wknd/core/models/Byline.java.

Modify the getData() method to return a type of ComponentData

import com.adobe.cq.wcm.core.components.models.datalayer.ComponentData;
...
public interface Byline {
    ...
    /***
     * Return data about the Byline Component to populate the data layer
     * @return ComponentData
     */
    ComponentData getData();
}

ComponentData is an object provided by AEM Core Components. It results in a JSON String, just like in the previous example, but also performs a lot of additional work.

Open the file BylineImpl.java at core/src/main/java/com/adobe/aem/guides/wknd/core/models/impl/BylineImpl.java.

Add the following import statements:

import com.adobe.cq.wcm.core.components.models.datalayer.ComponentData;
import com.adobe.cq.wcm.core.components.models.datalayer.builder.DataLayerBuilder;

Replace the getData() method with the following:

@Override
public ComponentData getData() {
    Resource bylineResource = this.request.getResource();
    // Use ComponentUtils to verify if the DataLayer is enabled
    if (ComponentUtils.isDataLayerEnabled(bylineResource)) {

        return DataLayerBuilder.extending(getImage().getData()).asImageComponent()
            .withTitle(this::getName)
            .build();

    }
    // return null if the Data Layer is not enabled
    return null;
}

The Byline component reuses parts of the Image Core Component to display an image representing the author. In the above snippet, the is used to extend the data layer of the Image component. This pre-populates the JSON object with all of the data about the image used. It also does some of the routine functions like setting the @type and the unique identifier of the component. Notice that the method is small!

The only property extended the withTitle which is replaced with the value of getName().

Open a terminal window. Build and deploy just the core module using your Maven skills:

$ cd aem-guides-wknd/core
$ mvn clean install -PautoInstallBundle

Return to the IDE and open the byline.html file under ui.apps

Update the HTL to use byline.data.json to populate the data-cmp-data-layer attribute:

  <div data-sly-use.byline="com.adobe.aem.guides.wknd.core.models.Byline"
    data-sly-use.placeholderTemplate="core/wcm/components/commons/v1/templates.html"
    data-sly-test.hasContent="${!byline.empty}"
-   data-cmp-data-layer="${byline.data}"
+   data-cmp-data-layer="${byline.data.json}"

Remember we are now returning an object of type ComponentData. This object includes a getter method getJson() and this is used to populate the data-cmp-data-layer attribute.

Open a terminal window. Build and deploy just the ui.apps module using your Maven skills:

$ cd aem-guides-wknd/ui.apps
$ mvn clean install -PautoInstallPackage

Return to the browser and reopen the page with the Byline component added: .

Open the browser’s developer tools and enter the following command in the Console:

window.adobeDataLayer.getState();

Navigate beneath the response under component to find the instance of the byline component:

You should see an entry like the following:

byline-136073cfcb:
    @type: "wknd/components/byline"
    dc:title: "Stacey Roswells"
    image:
        @type: "image/jpeg"
        repo:id: "142658f8-4029-4299-9cd6-51afd52345c0"
        repo:modifyDate: "2019-10-25T23:49:51Z"
        repo:path: "/content/dam/wknd/en/contributors/stacey-roswells.jpg"
        xdm:tags: []
    parentId: "page-30d989b3f8"
    repo:modifyDate: "2019-10-18T20:17:24Z"

Observe that there is now an image object within the byline component entry. This has a lot more information about the asset in the DAM. Also observe that the @type and the unique id (in this case byline-136073cfcb) have been automatically populated, and the repo:modifyDate which indicates when the component was modified.

Another example of extending the data layer can be viewed by inspecting the ImageList component in the WKND code base:

• ImageList.java - Java interface in the core module.
• ImageListImpl.java - Sling Model in the core module.
• image-list.html - HTL template in the ui.apps module.