JPA Criteria API with multiple parameters

Question

I need to make a search method that uses the JPA Criteria API with multiple parameters. Now the problem is that not every parameter is required. So some could be null, and t

Answer 1

Take a look at this site JPA Criteria API. There are plenty of examples.

Update: Providing a concrete example

Let's search for Accounts with a balance lower than a specific value:

SELECT a FROM Account a WHERE a.balance < :value

First create a Criteria Builder

CriteriaBuilder builder = entityManager.getCriteriaBuilder();

CriteriaQuery accountQuery = builder.createQuery(Account.class);
Root accountRoot = accountQuery.from(Account.class);
ParameterExpression value = builder.parameter(Double.class);
accountQuery.select(accountRoot).where(builder.lt(accountRoot.get("balance"), value));

To get the result set the parameter(s) and run the query:

TypedQuery query = entityManager.createQuery(accountQuery);
query.setParameter(value, 1234.5);
List results = query.getResultList();

BTW: The entityManager is injected somewhere in an EJB/Service/DAO.