I have to write a method where I pass it some arguments and depending on which arguments are empty it modifies the query I need to execute at the end.
E.g. if I want to select from a table Customer
that has an ID
, name
, surname
and address
the starting query would be SELECT * FROM Customer WHERE ID=myId AND name=myName AND surname=mySurname
(and now we check if the address I sent is empty, if it is NOT, add it to the query).
I know how to do this in C#, by simply doing a starting string and then just adding to it and using ExecuteStoreQuery directly, but how would this look in Java? Is Criteria Builder a viable tool for this?
Thank you so much!
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Answer
Using a CriteriaQuery, it is possible to do something like that (using Static JPA Metamodel Classes):
public List<Customer> findCustomer(Long myId, String myName, String mySurName, String myAddress) { CriteriaBuilder cb = enitityManager.getCriteriaBuilder(); CriteriaQuery<Customer> query = cb.createQuery(Customer.class); Root<Customer> root = query.from(Customer.class); List<Predicate> predicates = new ArrayList<>(); predicates.add(cb.equal(root.get(Customer_.ID), myId)); predicates.add(cb.equal(root.get(Customer_.NAME), myName)); predicates.add(cb.equal(root.get(Customer_.SURNAME), mySurName)); if(address != null) { predicates.add(cb.equal(root.get(Customer_.ADDRESS), myAddress)); } query.select(root).where(cb.and(predicates.toArray(new Predicate[0]))); return entityManager.createQuery(query).getResultList(); }
In this case, the address will only be checked if it is not null
.
Another example without using Static JPA Metamodel (not 100% sure about this):
public List<Customer> findCustomer(Long myId, String myName, String mySurName, String myAddress) { CriteriaBuilder cb = enitityManager.getCriteriaBuilder(); CriteriaQuery<Customer> query = cb.createQuery(Customer.class); Root<Customer> root = query.from(Customer.class); List<Predicate> predicates = new ArrayList<>(); predicates.add(cb.equal(root.get("ID"), myId)); predicates.add(cb.equal(root.get("name"), myName)); predicates.add(cb.equal(root.get("surename"), mySurName)); if(address != null) { predicates.add(cb.equal(root.get("address"), myAddress)); } query.select(root).where(cb.and(predicates.toArray(new Predicate[0]))); return entityManager.createQuery(query).getResultList(); }