I am having problems to implement a search in a PostgreSQl table. The table contains columns with empty strng values that causes an error.

Some information from the column design:
Data type: character varying(20)
Default:
Not NULL: No
Primary key: No

My java class annotation for the column:
@Column(name = "codeClient")
private String codeClient;

This query string works when there is no "empty string" value:
SELECT c FROM Client c WHERE c.id = 765432

And my Json returns:
[{"id":765432,"nameClient":"JACK SMITH","codeClient":"234567890"}]


When I change the query to deal with a empty value:
SELECT c.id, c.nameClient, CASE c.codeClient WHEN '' THEN 'nonexistent' else c.codeClient END FROM Client c WHERE c.id = 765432

The query works, but the Json result misses de columns descriptions:
[[765432,"JACK SMITH","234567890"]]

To solve this problem, I change the query to return an object:
SELECT new ClientDTO(c.id, c.nameClient, CASE c.codeClient WHEN '' THEN 'nonexistent' else c.codeCliente END) FROM Client c WHERE c.id = 765432

But Hibernate can't solve when the result is an empty string:
Java.lang.IllegalArgumentException: org.hibernate.QueryException: could not instatiate class [ClientDTO] from tuple

I've tried to use JPA CriteriaBuilder. It works on simple querys, but due to the complexity, I could not implement a query that I need.

I can't change de database design and I need the Json result.

Anybody can help me?

Done. I cast the ArrayList result to a POJO object manually.


Client clie;
List<Client> clients = new ArrayList<Client>();

List<Object[]> clientsObj = manager.createQuery(query).getResultList();

for (Object[] itemObj : clientsObj) {
clie = new Client();

clie.setId(Long.parseLong(itemObj[0].toString()));
clie.setNameClient(itemObj[1].toString());
clie.setCodeClient(itemObj[2].toString());

clients.add(clie);
}

return clients;