我无法使JPA CriteriaBuilder equal（）谓词区分大小写

Question

I am building a REST-Interface for some Application and I use JPA and Hibernate to access a SQL-Database.

Now I am trying to check if a given nickname already exists.

I am doing it this way:

CriteriaBuilder builder = this.entityManager.getCriteriaBuilder();
CriteriaQuery<DBUser> query = builder.createQuery(DBUser.class);
Root<DBUser> from = query.from(DBUser.class);
Predicate uniqueNickname = builder.equal(from.get(DBUser_.nickName),newNickname);
query.select(from).where(uniqueNickname);
if (this.entityManager.createQuery(query).getResultList().size() == 0) {
   //ok 
} else {
   //not ok
}

If I now have a User TEst in the database and newNickname="teST" it puts the User TEst into the resultlist. (I checked what the name in the resultlist is and it says TEst) I am using the mysql connector "mysql-connector-java-6.0.6.jar".

Answer 1

Normally, CriteriaBuilder#equal is case-sensitive, you can achieve equals ignore case by comparing strings in uppercase variant:

Predicate uniqueNickname = builder.equal(builder.upper(from.<String>get(DBUser_.nickName)),
                                         newNickname.toUpperCase());

In your case, the DB ignore the case sensitive completely.

Checking your MySQL DB and change the collation setting (the collation with _ci suffix is case-insensitve)