Case Insensitive Queries with the AEM Query Builder

Recently, I needed to perform a query using the AEM Query Builder which was case insensitive. While I normally prefer using JCR SQL2 queries, in this case Query Builder was a better fit as I wanted consuming applications to be able to manipulate the query and doing so as a map is significantly easier than doing so as a string.

I was surprised to find that there was no native Query Builder Predicate for doing case insensitive queries so I ended up writing my own.

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The predicate works by lower casing the value and then using the XPath fn:lower-case method to compare to the field value in lower case.

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package com.perficient.adobe.predicates;

import java.util.Locale;
import java.util.Optional;

import com.day.cq.search.Predicate;
import com.day.cq.search.eval.AbstractPredicateEvaluator;
import com.day.cq.search.eval.EvaluationContext;

import org.osgi.service.component.annotations.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(factory = "com.day.cq.search.eval.PredicateEvaluator/equalsIgnoreCase")
public class CaseInsensitiveEquals extends AbstractPredicateEvaluator {

    private static final Logger log = LoggerFactory.getLogger(CaseInsensitiveEquals.class);

    static final String PREDICATE_PROPERTY = "property";
    static final String PREDICATE_VALUE = "value";
    static final String PREDICATE_LOCALE = "locale";

    @Override
    public String getXPathExpression(Predicate predicate, EvaluationContext context) {
        log.debug("Evaluating predicate: {}", predicate);
        String property = predicate.get(PREDICATE_PROPERTY);
        Locale locale = Optional.ofNullable(predicate.get(PREDICATE_LOCALE)).map(lt -> Locale.forLanguageTag(lt))
                .orElse(Locale.getDefault());
        String value = predicate.get(PREDICATE_VALUE).toLowerCase(locale).replace("'", "''");
        String query = String.format("fn:lower-case(@%s)='%s'", property, value);
        log.debug("Generated query: {}", query);
        return query;
    }
} 

Once the custom predicate is available in your application, it can be used in any Query Builder query as such:

path=/content/test
equalsIgnoreCase.property=test
equalsIgnoreCase.value=test
equalsIgnoreCase.locale=en_US 

The locale parameter is not required, but would generally be recommended unless the input will always be in the system default locale.