1. CIRCUIT
AN ADOBE DEVELOPER EVENT
PRESENTED BY CITYTECH, INC.
Use SlingQuery and
walk the tree with ease
Tomek Rękawek, Cognifide
@TomaszRekawek

2. Sling API
Resource parent = myResource.getParent();
for (Resource child : parent.getChildren()) {
if (child.adaptTo(ValueMap.class).containsKey("myProperty")) {
//...
}
}
efficient, especially for denormalized and well-
structured content[1]
easy to use
but:
a lot of while()s, iterators and nullchecks
code complexity is growing fast
[1] Efficient content structures and queries in CRX

3. Sling example
Find the first ancestor with a given template.
String path = "/content/geometrixx/en/products/triangle/jcr:content/par";
String homeTemplate = "/apps/geometrixx/templates/homepage";
Resource resource = resourceResolver.getResource(path);
while ((resource = resource.getParent()) != null) {
if (!resource.isResourceType("cq:Page")) {
continue;
}
ValueMap map = resource.adaptTo(ValueMap.class);
String cqTemplate = map.get("jcr:content/cq:template");
if (homeTemplate.equals(cqTemplate)) {
break;
}
}
resource.getPath();

4. SlingQuery example
import static com.cognifide.sling.query.api.SlingQuery.$;
Resource resource = getResource("/content/geometrixx/en/products/triangle/jcr:content/par");
$(resource)
.closest("cq:Page[jcr:content/cq:template=/apps/geometrixx/templates/homepage]")
$()is a valid method name in Java,
it wraps resource(s) into an iterable SlingQuery
collection
each method transforms the existing collection
into a new one
API inspired by jQuery

5. Get all text components
from the parsys
r = getResource("/content/geometrixx/en/jcr:content/rightpar/teaser")
SlingQuery collection = $(r)
.closest("cq:PageContent")
.find("foundation/components/parsys#par")
.children("foundation/components/text")
for (Resource c : collection) {
println c.path
}
each method returns new collection
SlingQueryobject implements Iterable

6. Breadcrumbs
r = getResource("/content/geometrixx/en/products/mandelbrot/overview/jcr:content/par")
Iterable<Page> breadcrumbs = $(r)
.parents("cq:Page")
.not("[jcr:content/hideInNav=true]")
.map(Page.class)
for (Page p : breadcrumbs) {
println p.title
}
map()method creates a new Iterable<>
adapting each resource to a given class
resource.adaptTo(Page.class)
approach compatible with Sling Models

7. Selector string
r = getResource("/content/geometrixx/en/products/mandelbrot")
$(r)
.children("cq:PageContent")
.children("foundation/components/parsys")
.children("#title[jcr:title=Best in class][type=large]:first")
selector format
resource type or node type
#resource-name
attributes in []
modifiers, each prepended by :
all elements are optional

8. Advanced selectors
r = getResource("/content/geometrixx")
$(r)
.find("[text*=square]:not(cq:PageContent):first")
.closest("cq:Page")
.find("#title, #image, #par:parent")
:not()accepts any valid selector
:not(:not(:not(:first)))
:parent- only resources having children
there is a number of operators for square brackets
alternatives can be separated with a comma

9. Random image
rnd = new java.util.Random()
r = getResource("/content/dam/geometrixx/travel")
$(r)
.children("dam:Asset")
.filter({ rnd.nextFloat() > 0.9 } as Predicate)
.first()
in Java it'd look like this:
// ...
.filter(new Predicate<Resource>() {
@Override
public boolean accepts(Resource resource) {
return rnd.nextFloat() > 0.9;
}
});

10. Siblings but not me
r = getResource("/content/geometrixx/en/products/mandelbrot/jcr:content/par/image")
myPage = $(r).closest("cq:Page")
result = myPage
.siblings("cq:Page")
.not(myPage)
the SlingQuery collection is immutable
each method returns a new collection
any Iterable<Resource>may be used as a filter

11. Find all pages with
given template
$(resourceResolver)
.find("cq:PageContent[cq:template=/apps/geometrixx/templates/homepage]")
.parent()
$(resourceResolver)creates a collection
containing /
find()iterates over the whole subtree

12. Search strategy
r = getResource("/content/geometrixx/en")
result = $(r)
.searchStrategy(DFS)
.find("cq:Page")
for (Resource c : result) {
println c.path
}
strategies: DFS, BFS, QUERY
QUERYtries to rewrite find()selector into JCR-
SQL2
the result is filtered once more

13. Find method vs JCR
find()is powerful but may be dangerous
it should be used only for small subtrees
if you want to query a large space, use JCR-SQL[2]
or XPath
if your SlingQuery processes more than 100
resources, you'll get a warning in the logs:
28.05.2014 13:35:49.942 *WARN* [0:0:0:0:0:0:0:1 [1401276949857] POST /bin/groovy
console/post.json HTTP/1.1] SlingQuery Number of processed resources exceeded 10
0. Consider using a JCR query instead of SlingQuery. More info here: http://git.
io/h2HeUQ

14. Laziness
result = $(resourceResolver)
.searchStrategy(DFS)
.find()
.slice(10, 20)
result.toString()
we don't query resources unless we need them
invoking the SlingQuery method adds a new
function to the chain
functions are executed by the final iterator (like
the one created by the for()loop)
all functions are lazy
expect the last()function

15. Resources
code & docs
global Maven repository
https://github.com/Cognifide/Sling-Query
<dependency>
<groupId>com.cognifide.cq</groupId>
<artifactId>sling-query</artifactId>
<version>1.4.4</version>
</dependency>

16. Questions?

17. Thank you!