How to create custom query predicate in CQ

Use Case: Your search has some custom requirement that can not be covered by existing predicate

Pre requisite:

• http://www.pro-vision.de/content/medialib/pro-vision/production/adaptto/2011/2011_querybuilder-pdf/_jcr_content/renditions/rendition.file/2011_querybuilder.pdf
• http://dev.day.com/docs/en/cq/current/dam/customizing_and_extendingcq5dam/query_builder.html
• http://dev.day.com/docs/en/cq/current/javadoc/com/day/cq/search/QueryBuilder.html
• http://dev.day.com/docs/en/cq/current/javadoc/com/day/cq/search/eval/PredicateEvaluator.html

Example: 

Suppose you want to create a custom predicate to copare and sort case sensitive property.
Your predicate expression will look like

-----Signature -----

path=<Path under which search would be performed>

type=<node type>

customcase.property=<property name for which case sensitive search needs to be performed>

customcase.fulltext=<Search Text>

customcase.case=upper/lower/UPPER/LOWER/no_case/NO_CASE

orderby=customcase

You can test these example after deploying code HOST:PORT/libs/cq/search/content/querydebug.html

---- Example 1 (Find all node with subtitle as "MAIL" and do upper case compare) -----

path=/content/geometrixx/en

type=cq:Page

customcase.property=jcr:content/subtitle

customcase.fulltext=MAIL

customcase.case=upper

orderby=customcase

---- Example 2 (find all node and sort by subtitle property) -----

path=/content/geometrixx/en

type=cq:Page

customcase.property=jcr:content/subtitle

customcase.case=no_case

orderby=customcase

	import java.util.Comparator;
	import javax.jcr.query.Row;
	import org.apache.felix.scr.annotations.Component;
	import org.apache.sling.api.resource.ValueMap;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;
	import com.day.cq.search.Predicate;
	import com.day.cq.search.eval.AbstractPredicateEvaluator;
	import com.day.cq.search.eval.EvaluationContext;
	/**
	* Custom class to support case sensitive compare
	* path=
	* type=
	* customcase.property=
	* {optional} customcase.fulltext=
	* customcase.case=upper/lower/UPPER/LOWER/no_case/NO_CASE
	* orderby=customcase
	* @author yogeshupadhyay
	*
	*/
	@Component(metatype =false, factory="com.day.cq.search.eval.PredicateEvaluator/customcase")
	public class CustomCasePredicate extends AbstractPredicateEvaluator {
	private static final Logger logger = LoggerFactory.getLogger(CustomCasePredicate.class);
	public static final String PROPERTY = "property";
	public static final String FULL_TEXT = "fulltext";
	public static final String CASE = "case";
	public static final String LOWER_CASE = "lower";
	public static final String UPPER_CASE = "upper";
	public static final String NO_CASE = "no_case";
	@Override
	public boolean includes(Predicate predicate, Row row,
	EvaluationContext context) {
	if(predicate.hasNonEmptyValue(PROPERTY)){
	return true;
	}
	return super.includes(predicate, row, context);
	}
	/**
	* Create custom Xpath expression based on property
	*/
	@Override
	public String getXPathExpression(Predicate predicate,
	EvaluationContext context) {
	if(!predicate.hasNonEmptyValue(PROPERTY)){
	return null;
	}
	if(predicate.hasNonEmptyValue(PROPERTY) && null==predicate.get(FULL_TEXT)){
	return super.getXPathExpression(predicate, context);
	}
	if(predicate.get(CASE).equalsIgnoreCase(LOWER_CASE)){
	return "fn:lower-case(@"+predicate.get(PROPERTY)+")='"+predicate.get(FULL_TEXT)+"'";
	}
	if(predicate.get(CASE).equalsIgnoreCase(UPPER_CASE)){
	return "fn:upper-case(@"+predicate.get(PROPERTY)+")='"+predicate.get(FULL_TEXT)+"'";
	}
	if(predicate.get(CASE).equalsIgnoreCase(NO_CASE)){
	return "fn:lower-case(@"+predicate.get(PROPERTY)+")='"+predicate.get(FULL_TEXT).toLowerCase()+"'";
	}
	// TODO Auto-generated method stub
	return super.getXPathExpression(predicate, context);
	}
	/**
	* Some workaround is done to handle multi value property
	* Multivalue is sorted based on first value in Array
	*/
	@Override
	public Comparator<Row> getOrderByComparator(final Predicate predicate, final EvaluationContext context) {
	return new Comparator<Row>() {
	public int compare(Row r1, Row r2) {
	String[] property1;
	String[] property2;
	try {
	if(null!=r1&&null!=r2&&null!=predicate.get(PROPERTY)){
	ValueMap valueMap1 = context.getResource(r1).adaptTo(ValueMap.class);
	ValueMap valueMap2 = context.getResource(r2).adaptTo(ValueMap.class);
	property1 = valueMap1.get(predicate.get(PROPERTY),String[].class);
	property2 =valueMap2.get(predicate.get(PROPERTY),String[].class);
	boolean isCompare = null!=property1 && null!=property2;
	if(isCompare) logger.debug("value "+ property1[0] + " "+ property2[0]);
	if(isCompare && predicate.get(CASE).equalsIgnoreCase(LOWER_CASE)){
	return property1[0].toLowerCase().compareTo(property2[0].toLowerCase());
	}
	if(isCompare && predicate.get(CASE).equalsIgnoreCase(UPPER_CASE)){
	return property1[0].toUpperCase().compareTo(property2[0].toUpperCase());
	}else{
	return isCompare ? property1[0].compareToIgnoreCase(property2[0]):1;
	}
	}
	} catch (Exception e) {
	logger.error(e.getMessage());
	e.printStackTrace();
	}
	return 1;
	}
	};
	}
	}

view raw CustomPredicate.java hosted with ❤ by GitHub

One more example http://labs.sixdimensions.com/blog/joe-gergis/2013-07-10/custom-predicateevaluators-or-how-i-learned-stop-worrying-and-love

And one more

https://github.com/Adobe-Marketing-Cloud/aem-docs-custom-predicate-evaluator/blob/master/src/main/java/com/adobe/aem/docs/search/ReplicationPredicateEvaluator.java

Note: As you can see, Code is not optimal. It is just an example of how you can create your own predicate. Also Example assumes that you know how to import dependencies for this code. Let me know if you have any question.