Case insensitive search with Predicate and Criteria API

Issue

I have currently implemented a dynamic query builder that works perfectly if my query conditions are spelled correctly. Since this might not be always the case I need a solution that is flexible enough to take any variation of the condition, primarily supporting case insensitivity.

Current specification’s toPredicate method override code looks like this:

final List<Predicate> predicates = new ArrayList<Predicate>();

    Path<String> username = root.get("username");
    Path<String> agentCode = root.get("agentCode");
    Path<EntityStatus> status = root.get("status");
    Path<String> firstname = root.get("firstName");
    Path<String> lastname = root.get("lastName");
    Path<String> email = root.get("eMail");


if(criteria.getUsername()!=null && !criteria.getUsername().isEmpty()) {
      predicates.add(cb.equal(username, criteria.getUsername()));
    }

    if(criteria.getAgentCode()!=null && !criteria.getAgentCode().isEmpty()) {
      predicates.add(cb.equal(agentCode, criteria.getAgentCode()));
    }

    if(criteria.getFirstName()!=null && !criteria.getFirstName().isEmpty()) {
      predicates.add(cb.like(firstname, "%"+criteria.getFirstName()+"%"));
    }

    if(criteria.getLastName()!=null && !criteria.getLastName().isEmpty()) {
      predicates.add(cb.equal(lastname, criteria.getLastName()));
    }

    if(criteria.getEMail()!=null && !criteria.getEMail().isEmpty()) {
      predicates.add(cb.equal(email, criteria.getEMail()));
    }

    if(criteria.getStatus()!=null) {
      predicates.add(cb.equal(status, criteria.getStatus()));
    }

    return cb.and(predicates.toArray(new Predicate[predicates.size()]));
  }

And my repository interface that is being called from the service layer looks like this.

public interface UserRepo extends PagingAndSortingRepository<User, Long> {
     List<User> findAll(Specification spec);
}

Solution

Normally, you achieve the case-insensitivity with using method equalsIgnoreCase().

However in this case you just parse values to be compared without implementing the comparison itself. Thus you can parse all the values in lower-case using the method toLowerCase() forcing them to be compared case insensitively.

predicates.add(cb.equal(email.toLowerCase(), criteria.getEMail().toLowerCase()));

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Edit: I have taken a look on the JavaEE documentation of CriteriaBuilder and found the method lower() which may be helpful.

Answered By – Nikolas Charalambidis

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