AEM - Read Tags and Children

_cq_dialog.xml

<jcr:root xmlns:sling="http://sling.apache.org/jcr/sling/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0"
          xmlns:nt="http://www.jcp.org/jcr/nt/1.0" xmlns:cq="http://www.day.com/jcr/cq/1.0"
          xmlns:granite="http://www.adobe.com/jcr/granite/1.0"
          jcr:primaryType="nt:unstructured"
          jcr:title="Faceted Navigation"
          sling:resourceType="cq/gui/components/authoring/dialog">
    <content
        jcr:primaryType="nt:unstructured"
        sling:resourceType="granite/ui/components/coral/foundation/container"
        granite:class="cmp-navigation__editor">
        ...
        <tags
          jcr:primaryType="nt:unstructured"
          sling:resourceType="cq/gui/components/coral/common/form/tagfield"
          fieldLabel="Show Tags and Children"
          fieldDescription="If set, the results will match the selected tags on Navigation component."
          rootPath="/content/cq:tags"
          multiple="{Boolean}true"
          name="./naviTags"/>
        ...

AemTag.java

import org.apache.sling.api.resource.NonExistingResource;
..
public class AemTag {
..  
  @Expose
  private final String id;
  
  @Expose
  private final String title;
  
  public AemTag(final Tag tag, ResourceResolver resolver, Locale locale, int levels) throws IllegalArgumentException {
  ..  
    Resource tagResource = resolver.resolve(tag.getPath());
    if (tagResource instanceof NonExistingResource) {
      throw new IllegalArgumentException("Tag resource missing for " + tag.getPath());
    }

    String tagTitle = tag.getTitle();

    if (levels == 0) {
      this.id = tag.getTagID();
      this.title = tagTitle;
      this.children = null; // Gson, by default, won't include null fields. Call serializeNulls() to change this.
    } else {
      List<AemTag> children = StreamSupport.stream(tagResource.getChildren().spliterator(), false)
                .map(r -> r.adaptTo(Tag.class))
                .filter(Objects::nonNull)
                .map(t -> new AemTag(t, resolver, locale, levels - 1))
                .collect(Collectors.toList());

            this.id = tag.getTagID();
            this.title = tagTitle;
            this.children = children;
    }
  }
}

navi.html

<!-- Compoentn primary html -->
<nav data-sly-use.model="com.web.models.component.Navi"
     data-sly-use.template="core/wcm/components/commons/v1/templates.html"
     id="${navi.id}"
     class="cmp-navi"
     data-cmp-data-layer="${navi.data.json}"
     aria-label="${navi.accessibilityLabel}">
    <!-- Temporarily displaying json of the tags selected to be shown -->
    <div>
        <p>${model.naviTagsJson}</p>
    </div>
</nav>
<sly data-sly-call="${template.placeholder @ isEmpty=!hasContent, classAppend='cmp-navigation'}"></sly>

Navi.java

package com.web.models.component;
..
import com.day.cq.tagging.Tag;
import com.day.cq.tagging.TagManager;
...
@Model(adaptables = Resource.class,
        defaultInjectionStrategy = DefaultInjectionStrategy.OPTIONAL,
        resourceType = EventList.RESOURCE_TYPE)
@Exporter(name = "jackson", extensions = "json")
public class Navi extends ComponentSlingModel {
  ...
  private static final Gson GSON = new GsonBuilder().disableInnerClassSerialization().excludeFieldsWithoutExposeAnnotation().create();
  ...
  @Inject
  @Named("naviTags")
  private String[] naviTags;
  ...
  private List<String> naviTagsList = new ArrayList<>();
  ...
  @PostConstruct
  public void postConstruct() throws Exception {
    if (naviTags!=null && naviTags.length > 0) {
      naviTagsList.addAll(Arrays.asList(naviTags));

      Iterator<String> navIterator = naviTagsList.iterator();
      while (navIterator.hasNext()) {
        String tagName = navIterator.next();
        Tag userTag = tagManager.resolve(tagName);
        
        if (userTag != null) {
          AemTag aemTag = new AemTag(userTag, getResourceResolver(), locale, 0);
          if (aemTag != null) {
            tagsWithChildren.put(aemTag.getTitle(), getChildren(aemTag, userTag, locale));
          }
        }
      }
    }
    ....
  } // End postConstruct
  
  private List<AemTag> getChildren(final AemTag aemTag, final Tag userTag, final Locale locale) {
    Resource tagResource = getResourceResolver().resolve(userTag.getPath());
    
    List<AemTag> children = StreamSupport.stream(tagResource.getChildren().spliterator(), false)
                .map(r -> r.adaptTo(Tag.class))
                .filter(Objects::nonNull)
                .map(t -> new AemTag(t, getResourceResolver(), locale, 0))
                .collect(Collectors.toList());

    return children;
  }
  
  public String getNaviTagsJson() {
    return GSON.toJson(getTagsWithChildren());
  }