I ended up writing a simple BMP entity bean that only provides a create() method through the home interface. This bean is db platform independent, since (at least in my case) it only uses one SQL 92 compliant statement. However, it is not db-schema independent for obvious reasons. my current requirements dictate that I have two versions of my entity dd's, one for the default JbossCMP-generated schema and one set of dd's mapped to existing schema. so, i really only need to have two versions of my BMP entity, and since it basically only has one method (ejbCreate()) it works out pretty well.
however, I think that the ability to specify a primary key field as 'datasource-provided' in the jbosscmp-jdbc dd would be a useful feature in JBoss. Is this logically sound or am I missing something here? JBoss would only have to check for the presence of this tag and, if present, not include this column in the generated SQL insert statement. thoughts? Justin > I had this exact scenario with using auto-generated PK's in Postgres > (serial datatype). Being new to EJB/JBoss, my short term solution just > to get something working was to actually use my datasource and query the > sequence during the creation of the EJB. This works fine, but obviously > ties your bean to a specific datasource & database. > > My next plan is to maybe use a stateless session bean and have some sort > of resource manager facility that the beans could use to request PK > id's. The resource manager could do the work of actually using the > underlying sequences and feed the information back. With this, I would > (at worst) have a single class that would have to change in order to > deploy on a different DB/datasource. When I actually get around to it, > I'm pretty sure I should be able to find a way to dynamically load some > settings that would even eliminate that altogether. > > Being a newbie, maybe somebody else has a better solution. If so, I'd > sure be interested in it as well. > > gary. > > Justin Casp wrote: > >Hi list, > >I'm trying to use an auto-numbering strategy for a bean's PK, e.g., > > sequences on Postgres or Identity on MS SQL. The bean's PK type is > > Integer. When I attempt to not set a specific value for this field in > > ejbCreate() (assuming that the DB will assign a value for me), I get the > > following error using Postgres: > >11:52:09,393 ERROR [MyBean] Could not create entity > >java.sql.SQLException: ERROR: ExecAppend: Fail to add null value in not > > null attribute mybeanID > > > > at org.postgresql.core.QueryExecutor.execute(Unknown Source) > > at org.postgresql.Connection.ExecSQL(Unknown Source) > > at org.postgresql.jdbc2.Statement.execute(Unknown Source) > > at org.postgresql.jdbc2.Statement.exec > > at org.postgresql.jdbc2.PreparedStatement.executeUpdate(Unknown > >Source) > > at > >org.jboss.resource.adapter.jdbc.local.LocalPreparedStatement.executeUpdate > >(LocalPreparedStatement.java:308) uteUpdate(Unknown Source) > > > >etc. > > > >I get a similar error using the MSSQL driver with their DB. > >Basically, I want to know if it is possible to do this sort of thing in a > >DB-agnostic manner (well, as much as possible, anyway- I would have to > > assume the DB supports an auto-numbering scheme). The Postgres exception > > above looks like the JDBC driver might be the part having problems. > > > >One alternative is to use an external ID generator, similar to this > > article: http://www.theserverside.com/patterns/thread.jsp?thread_id=4228 > > > >But the problem with this is that the database that I'm working with is > > not exclusively accessed by JBoss. I have to share it with existing > > non-java legacy apps that use the sequence/Identity feature, and changing > > these apps is not really an option. > > > >I'm thinking that this is a fairly common problem, but I couldn't find > > much on the web specific to JBoss or JDBC/Postgres/MSSQL. > > > >Any tips on how to resolve this issue would be much appreciated. > >Thanks! > >Justin > > > > > >_______________________________________________________________ > > > >Sponsored by: > >ThinkGeek at http://www.ThinkGeek.com/ > >_______________________________________________ > >JBoss-user mailing list > >[EMAIL PROTECTED] > >https://lists.sourceforge.net/lists/listinfo/jboss-user > > _______________________________________________________________ > > Sponsored by: > ThinkGeek at http://www.ThinkGeek.com/ > _______________________________________________ > JBoss-user mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/jboss-user ---------------------------------------------------------------------------- Bringing you mounds of caffeinated joy >>> http://thinkgeek.com/sf <<< _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
