Re: [dbforms] Connection.setAutoCommit(false) in the Interceptor

[Shawn]

If you set connection.setAutoCommit(false) to open a transaction, and 
then, if
you notice that your set of queries fail, then you should also call the
connection.rollback() operation to discard them.
On-the-fly example (hope it works ;^):

So in this case if you have an interceptor like:

 public int preInsert(HttpServletRequest request, Hashtable fieldValues,
          DbFormsConfig config, Connection con)
            throws ValidationException {
        return orderShip(fieldValues);

            }

 public int orderShip (String productId, String orderId)
  {
        boolean ok = true;
     try
     {
       con.setAutoCommit(false);
       updateOrderItem(productId, orderId);
       con.commit();
     }
     catch (SqlException ex)
     {
        ok= false;
       con.rollback();
     }
     finally
     {
      if (con != null)
        con.close();
     }
      if (ok) return GRANT_OPERATION;
      else return DENY_OPERATION;
  }
In this case then you wouldn't need  con.setAutoCommit(true);   --would 
you?

In this case then if the transactions before the main transaction fails, 
and DENY_OPERATION is returned,
  public void orderShip (String productId, String orderId)
  {
     try
     {
       con.setAutoCommit(false);
       updateOrderItem(productId, orderId);
       con.commit();
     }
     catch (SqlException ex)
     {
       con.rollback();
     }
     finally
     {
       if (con != null)
         con.close();
     }
  }
Any database event checks if there is any interceptor object binded to 
the
current main table. If yes, the db event uses table.processInterceptors 
to
execute the interceptor's PRE_INSERT hook method.
If the interceptor ***returns a DENY_OPERATION code***, the table object 
fires
a SqlException catched by the Controller object.
The controller then calls cleanUpConnectionAfterException(con) method 
that:

- checks if the current connection belongs to an open transaction
  (con != null) && (!con.getAutoCommit())
  - if yes, calls
    con.rollback();
    con.setAutoCommit(true);
    to discard transaction db operations and set the autoCommitMode to ON
    to prevent to add more operations into the transaction queue.
Finally the controller executes closeConnections(connections) to
close the connection.
Your code example could be useful to build a transactional-interceptor 
test
case for dbforms...

Regards,
Luca
______________________________________________
Sunil Mishra, Manager, ADP Wilco (India) Private Limited
* +91-40-2340 8600 x-8202 ---- * +91-98490-61241




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--
Shawn
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