Question

I have a JUnit 4 test case with the Spring @Transactional annotation that saves an object, and then attempts to find it. The test case passes when I use this implementation:

@Override
public EventSummary findEventSummaryById(Integer id) {
    return em.find(EventSummary.class, id);
}

It fails when I use this implementation (and then change which method I call in the test case):

@Override
public EventSummary findEventSummary(Integer id) {
    Query query = em.createQuery("select es from EventSummary as es where es.id = :id");
    query.setParameter("id", id);
    EventSummary result = (EventSummary) query.getSingleResult();
    return result;
}

Answer 1

If you are using the default flush mode (AUTO) and if you are executing your query within a transaction, the JPA specification guarantees that a Query will not return stale or incorrect data:

3.6.2 Queries and FlushMode

The flush mode setting affects the
result of a query as follows.

When queries are executed within a
transaction, if FlushModeType.AUTO
is set on the Query object, or if the
flush mode setting for the persistence
context is AUTO (the default) and a
flush mode setting has not been
specified for the Query object, the
persistence provider is responsible
for ensuring that all updates to the
state of all entities in the
persistence context which could
potentially affect the result of the
query are visible to the processing of
the query. The persistence provider
implementation may achieve this by
flushing those entities to the
database or by some other means. If
FlushModeType.COMMIT is set, the
effect of updates made to entities in
the persistence context upon queries
is unspecified.

public enum FlushModeType {
    COMMIT,
    AUTO
}

If there is no transaction active, the
persistence provider must not flush to
the database.

Assuming that you are using AUTO, check the transactional side.