AEM Query Builder Optimization using Java Streams and Resource Filter

Problem statement:

Can Java Streams and Resource Filter be used as an alternative to Query Builder queries in AEM for filtering pages and resources based on specific criteria?


The query for the pages whose resurcetype = “wknd/components/page” and get child resources which have an Image component (“wknd/components/image”) and get the file reference properties into a list

Query builder query would be like this:

private void initModel() {
  Map < String, String > map = new HashMap < > ();
  map.put("path", resource.getPath());
  map.put("property", "jcr:primaryType");
  map.put("property.value", "wknd/components/page");

  PredicateGroup predicateGroup = PredicateGroup.create(map);
  QueryBuilder queryBuilder = resourceResolver.adaptTo(QueryBuilder.class);

  Query query = queryBuilder.createQuery(predicateGroup, resourceResolver.adaptTo(Session.class));
  SearchResult result = query.getResult();

  List < String > imagePath = new ArrayList < > ();

  try {
    for (final Hit hit: result.getHits()) {
      Resource resultResource = hit.getResource();
      Iterator < Resource > children = resultResource.listChildren();
      while (children.hasNext()) {
        final Resource child =;
        if (StringUtils.equalsIgnoreCase(child.getResourceType(), "wknd/components/image")) {
          Image image = modelFactory.getModelFromWrappedRequest(request, child, Image.class);
  } catch (RepositoryException e) {
    LOGGER.error("error occurered while getting result resource {}", e.getMessage());


This article discusses the use of Java Streams and Resource Filter in optimizing AEM Query Builder queries. The article provides code examples for using Resource Filter Streams to filter pages and resources and using Java Streams to filter and map child resources based on specific criteria. The article also provides optimization strategies for AEM tree traversal to reduce memory consumption and improve performance.

Resource Filter bundle provides a number of services and utilities to identify and filter resources in a resource tree.

Resource Filter Stream:

ResourceFilterStream combines the ResourceStream functionality with the ResourcePredicates service to provide an ability to define a Stream<Resource> that follows specific child pages and looks for specific Resources as defined by the resources filter script. The ResourceStreamFilter is accessed by adaptation.

ResourceFilterStream rfs = resource.adaptTo(ResourceFilterStream.class);
  .setBranchSelector("[jcr:primaryType] == 'cq:Page'")
  .setChildSelector("[jcr:content/sling:resourceType] != 'apps/components/page/folder'")


The ResourceFilter and ResourceFilteStream can have key-value pairs added so that the values may be used as part of the script resolution. Parameters are accessed by using the dollar sign ‘$’

rfs.setBranchSelector("[jcr:content/sling:resourceType] != $type").addParam("type","apps/components/page/folder");

Using Resource Filter Stream the example code would look like below:

private void initModel() {
  ResourceFilterStream rfs = resource.adaptTo(ResourceFilterStream.class);
  List < String > imagePaths = rfs.setBranchSelector("[jcr:primaryType] == 'cq:Page'")
    .setChildSelector("[jcr:content/sling:resourceType] == 'wknd/components/page'")
    .filter(r -> StringUtils.equalsIgnoreCase(r.getResourceType(), "wknd/components/image"))
    .map(r -> modelFactory.getModelFromWrappedRequest(request, r, Image.class).getFileReference())

Optimizing Traversals

Similar to indexing in a query there are strategies that you can do within a tree traversal so that traversals can be done in an efficient manner across a large number of resources. The following strategies will assist in traversal optimization.

Limit traversal paths

In a naive implementation of a tree traversal, the traversal occurs across all nodes in the tree regardless of the ability of the tree structure to support the nodes that are being looked for. An example of this is a tree of Page resources that has a child node of jcr:content which contains a subtree of data to define the page structure. If the jcr:content node is not capable of having a child resource of type Page and the goal of the traversal is to identify Page resources that match specific criteria then the traversal of the jcr:content node can not lead to additional matches. Using this knowledge of the resource structure, you can improve performance by adding a branch selector that prevents the traversal from proceeding down a nonproductive path

Limit memory consumption

The instantiation of a Resource object from the underlying ResourceResolver is a nontrivial consumption of memory. When the focus of a tree traversal is obtaining information from thousands of Resources, an effective method is to extract the information as part of the stream processing or utilize the forEach method of the ResourceStream object which allows the resource to be garbage collected in an efficient manner.


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