Spring Data mongo case insensitive like query

I know this is an old question. I just found the solution in another post. Use $regex and $options as below:

@Query(value = "{'title': {$regex : ?0, $options: 'i'}}")
Foo findByTitleRegex(String regexString);

see the original answer: https://stackoverflow.com/a/19068401

You can try something like below. Assumes you have a User pojo class.

Using MongoTemplate

i option for case insensitive:

Criteria regex = Criteria.where("username").regex(".*ab.*", "i");      
mongoOperations.find(new Query().addCriteria(regex), User.class);

Using MongoRepository (Case sensitive)

List<User> users = userRepository.findByUserNameRegex(".*ab.*");

interface UserRepository extends MongoRepository<User, String> {
     List<User> findByUserNameRegex(String userName);
}

Using MongoRepository with Query dsl (Case sensitive)

List<User> users = userRepository.findByQuery(".*ab.*");

interface UserRepository extends MongoRepository<User, String> {
     @Query("{'username': {$regex: ?0 }})")
     List<User> findByQuery(String userName);
}

For Non-Regex based query you can now utilize case insensitive search/sort through collation with locale and strength set to primary or secondary:

Query query = new Query(filter);
query.collation(Collation.of("en").
                  strength(Collation.ComparisonLevel.secondary()));
mongoTemplate.find(query,clazz,collection);

@Repository
public interface CompetenceRepository extends MongoRepository<Competence, String> {

    @Query("{ 'titre' : { '$regex' : ?0 , $options: 'i'}}")
    List<Competence> findAllByTitreLikeMotcle(String motCle);
}

Should works perfectly ,it works in my projects.for words in French too

In repository pattern I tried this and worked

@Query("{ 'username' : ?0 }.collation( { locale: 'en', strength: 2 } )")

User findByUserName(String name);