Re: PB API: DELETE object -> OptimisticLockException

[Armin Waibel]

Hi,

[EMAIL PROTECTED] wrote:

Hi all,

we use optimistic locking using timestamp.
is there a best practice to not get the OptimisticLockException
(returned by the method JdbcAccessImpl.executeDelete(ClassDescriptor cld,
Object obj) )
when we try to delete a non-existent object in a database ?
What do you expect instead? Another exception e.g. 
PersistenceBrokerException say that the object does not exists,
or should the method return without any exception thrown (e.g. only
a log info message)?

Below you can find a workaround for your problem by adding a new method 
to JdbcAccessImpl class. When the statement does not match, check before 
throw an OptimisticLockingException if object does exist. But I don't 
know that this will be the best way to fix your problem.

regards,
Armin
### change in excute delete (line ~132)

            if (stmt.executeUpdate() == 0 && cld.isLocking()) //BRJ
            {
                if(checkExistence(cld, obj))
                {
                    throw new OptimisticLockException("Object has been 
modified by someone else", obj);
                }
                else
                {
                    logger.info("Seems Object "+obj+" does not exist, 
can't delete.");
                }
            }

### add method
private boolean checkExistence(ClassDescriptor cld, Object obj) throws 
PersistenceBrokerException
    {
        boolean result = false;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try
        {
            stmt = 
broker.serviceStatementManager().getSelectByPKStatement(cld);
            broker.serviceStatementManager().bindSelect(stmt, new 
Identity(obj, broker), cld);
            rs = stmt.executeQuery();
            if(rs.next()) result = true;
        }
        catch (SQLException e)
        {
            throw new PersistenceBrokerSQLException("Can't check 
existence of object: " + obj, e);
        }
        finally
        {
            if(stmt != null)
            {
                broker.serviceStatementManager().closeResources(stmt, rs);
            }
        }
        return result;
    }

Obviously, we want to keep the locking='true' in the cld.

Thanks!



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