PostgreSQL JDBC Null String taken as a bytea

Question

If entity.getHistory() is null following code snippet:

(getEntityManager() returns spring injected EntityManager, database field history type is: text or varchar2(2000)

Query query = getEntityManager().createNativeQuery("insert into table_name(..., history, ....) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)")
[...]
.setParameter(6, entity.getHistory())
[...]

query.executeUpdate();

Gives strange exception:

17/11/11 06:26:09:009 [pool-2-thread-1]  WARN util.JDBCExceptionReporter:100 - SQL Error: 0, SQLState: 42804
17/11/11 06:26:09:009 [pool-2-thread-1] ERROR util.JDBCExceptionReporter:101 - ERROR: **column "history" is of type text but expression is of type bytea**

Hint: You will need to rewrite or cast the expression.

Problem occurred only in this configuration:
OS: CentOS release 5.6 (Final)
Java: 1.6.0_26
DB: PostgreSQL 8.1
JDBC Driver: postgresql-9.1-901.jdbc4
Application Server: apache-tomcat-6.0.28

Everything is working fine on few other configurations or when history is empty string. Same statement executed from pgAdmin works fine.

I guess problem is in PostgreSQL JDBC driver, is there some sensible reason to treat null string as a bytea value? Maybe some strange changes between Postgres 8 and 9?

Answer 1

There's a simple fix: when you're building the query string, if a parameter is going to be null -- use "null" instead of "?".

As @araqnid says, Hibernate is incorrectly casting null values into type bytea because it doesn't know any better.

Answer 2

Since you're calling setParameter(int,Object) with a null value, at a guess the entity manager has no idea which persistence type to use to bind the parameter. Istr Hibernate having a predilection for using SerializableType, which would equate to a bytea.

Can you use the setParameter method that takes a Parameter object instead, so you can specify the type? I haven't really used JPA, so can't give a detailed pointer.

(IMHO this is your just desserts for abusing EntityManager's native-sql query interface to do inserts, rather than actually mapping the entity, or just dropping through to JDBC)

Answer 3

Using Hibernate specific Session API works as a workaround:

String sql = "INSERT INTO person (id, name) VALUES (:id, :name)";
Session session = em.unwrap(Session.class);
SQLQuery insert = session.createSQLQuery(sql);
sql.setInteger("id", 123);
sql.setString("name", null);
insert.executeUpdate();

I've also filed HHH-9165 to report this issue, if it is indeed a bug.

Answer 4

Most of above answers are meaningful and helped me to narrow down issue.

I fixed issue for nulls like this:

setParameter(8, getDate(), TemporalType.DATE);