Learning by doing

I am so behind the times ... NHibernate 2.0.1 GA was released last fall and 2.1.0 Alphas are coming out. In the mean time, Hibernate.org has been subsumed by Redhat's JBoss. The url www.hibernate.org doesn't take you anywhere useful, and following the javascript menu to projects / services / hibernate still doesn't get you anywhere - pure garbage. It is clear that JBoss wants to sell you their enterprise build of Hibernate instead (that "Products" link works). I have been so busy with my day job that I haven't been keeping up. I work at a hospital, supporting Cerner Millenium - writing CCL, Perl, Python, Microsoft SQL (occasionally), and a bit of C#. Cerner CCL is a proprietary language that feels like a mash-up of Fortran IV and and an arcane dialect of SQL from 1976. The language used to run on VMS servers, but we have migrated to HP-UX, and I am OVERJOYED to have a choice of using a posix shell, ksh or csh. Also, I recently discovered that CCL al...

NHibernate 2.0 is not even close to release, but it is shaping up nicely. Oren Eini (His blog is called Ayende @ Rahien) has a list of interesting new features . Dario Quintana has something to say as well . He has contributed some code to the uNHAddins for Active Record Detached Query support . The Castle development team is considering pointing to NHibernate Trunk (which will be released as 2.0 eventually) so they/we can take advantage of the new features. If Castle Active Record uses NHibernate trunk, I would advise you to be diligent wit! your test code, and don't forget to run the Castle test code too. You can track Castle Project changes on FishEye .

Friday, I added an NHibernate mapping.hbm.xml template. I mainly wanted to show that the code generator can be used for other purposes than just Castle ActiveRecord, and NHibernate is an easy target. Jim R. has requested that I add HasMany (aka ManyToOne) mapping properties and attributes. I think this is going to push me to refactor the schema extraction code. Some of my future goals for the application are: 1. Full Model Generation (list of children, whether directly or indirectly through a many-to-many table) 2. User controllable plural-to-singular mapping. 3. Multi-database, using the Database Provider Factory. 4. Refactor code generation into a library (as I do with all projects) 5. Command-line code generation (supply at least a template and a list of tables) 6. Templates for other ORM tools (pure NHibernate, Rocky Lhotka's CSLA Business Objects, etc.)

Update 05/22/2007: No response from the community. I think Hammett is working on releasing a new version of Castle (It's much more than just ActiveRecord!), so I have not received any feedback on my patch. I have just posted patch AR-156 to Castle's ActiveRecord project to add support for XML free mapping of insert, update and delete stored procedures to ActiveRecord classes. This requires a bit of work, since the stored procedures must match the field order generated by NHibernate , rather than being controlled by the application developer. This means that we have to create the class normally, run it through a test cycle with logging turned on, capture the prepared statement's field order, and then re-write the stored procedure to match what NHibernate wants. This is because behind the scenes the stored procedure replaces a prepared sql statement that NHibernate would otherwise be using. This will be a mess to maintain until or unless someone contributes a patch to ...

NHibernate was released May 3, 2007 and they have a migration guide for those of you who do not follow changes in the svn. This release supports stored procedures, and as you can see in the screen shot above, I am working on adding SQL stored procedure generation to my ActiveRecord Generator. I have templates for INSERT, UPDATE and DELETE now, and I will write a SELECT by primary key today. It's too bad I can't just write an attribute to append to the NHibernate mapping file that ActiveRecord creates. I don't know if I will have to write my own ActiveRecord attributes, but the Castle Project seems very friendly to patches. This is very important because I would not really want to release a program that requires a patched library. I have found several bloggers who have created NHibernate + Stored Procedure samples, but none that have ActiveRecord samples (since we do not have the attributes yet). If you have been working on something, now is your chance to share. (...

[Update 1: finished the entry, and added some compilable code.] [Update 2: Updated the compilable code - improved the Property setter code.] Recently, I have been working on a project with Castle's ActiveRecord support. Since I am changing my database schema as I discover new requirements, and adapt to new data sources, I occasionally run into query / model / table mismatches. Now, gross mismatches cause NHibernate to choke, and refuse to accept my models, but if I have merely added a field, that will be ignored until insert time. Even then, it might not cause an exception if it is a nullable field. Now when I first started on this project, I wrote a simple SQL procedure that selected a list of fields from the database schema, walked through a cursor for each field and PRINTed code, then I would create a class file in Visual Studio 2005 and paste that code in. -- Get a list of tables SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME != 'sysdiagrams...

Since this is my first post on the subject, let me introduce the Castle project - a .Net framework that I have been exploring recently. It has a project that tries to mimic ActiveRecord in Ruby-On-Rails, although the Castle version of ActiveRecord uses NHibernate. The good news is that an ActiveRecord class doesn't require any XML configuration or mapping files. The somewhat bad news is that you DO have to declare your classes and populate them with properties, private members and AR mapping attributes. Since I will probably use SQLServer 2000, I will just write a few queries to extract the data type and field list for each table that I want to support. More on this later. For today, I wanted to extract the class-to-database mapping information that Castle's ActiveRecords feeds to NHibernate. I finally looked through the source code a bit and after a blind alley (NHibernate.Cfg Configuration is mostly for database connections), I ran across the ActiveRecordModel class...