Thursday, August 07, 2008

Testing OpenJPA SQL statements using a JDBCListener

I am currently designing something around FetchGroups in OpenJPA, and being a good Agile / Test Driven architect, I wanted to write a JUnit which asserts the actual SQL statement generated by this ORM (the purpose is to test the FROM/WHERE, the SQL should not include unncessary JOIN and columns, if that framework I'm building around FetchGroups works).

Initially I went off looking into e.g. good ol' P6spy (that's STILL around?). Then I mused around some (Spring?) AOP Interceptor for a JDBC Connection, this article on DW seemed a good starting point... But finally I realized that the following (OpenJPA specific; this is obviously not standard JPA) does the job perfectly (and may be useful to others, so posted here):
public class RememberingLastStatementJDBCListener extends AbstractJDBCListener {

private String lastSQL;

@Override
protected void eventOccurred(JDBCEvent event) {
if (event.getSQL() != null) {
// Note: This will be called several times, for different event.getType(); but it doesn't matter for this use.
this.lastSQL = event.getSQL();
}
}

public String getLastSQL() {
return this.lastSQL;
}

and then in the JUnit you can do like:

RememberingLastStatementJDBCListener rememberingLastStatementJDBCListener;

openJPAConnectionProperties.setProperty("openjpa.jdbc.JDBCListeners", RememberingLastStatementJDBCListener.class.getName());

OpenJPAEntityManager oem = OpenJPAPersistence.cast(em);
OpenJPAEntityManagerSPI oems = (OpenJPAEntityManagerSPI) oem;
OpenJPAConfiguration configuration = oems.getConfiguration();
JDBCConfiguration jdbcConfiguration = (JDBCConfiguration)configuration;
JDBCListener[] jdbcListeners = jdbcConfiguration.getJDBCListenerInstances();
for (JDBCListener listener : jdbcListeners) {
if (listener instanceof RememberingLastStatementJDBCListener) {
rememberingLastStatementJDBCListener = (RememberingLastStatementJDBCListener) listener;
}
}

SomeEntity e = new SomeEntity();
e.setName("Hallo World!");
em.persist(e);

// We *HAVE* to flush() at this point, otherwise the Listener won't (yet) have seen the Statement(s)
em.flush();

Assert.assertEquals("INSERT INTO APP.SOMEENTITY (ID, NAME) VALUES (?, ?)",
rememberingLastStatementJDBCListener.getLastSQL());

Don't you love Open Source frameworks, where you can dig into the code and figure this kind of stuff out? ;-)

1 Comments:

Anonymous Anonymous said...

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13 April, 2009 09:00  

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