Thursday, May 17, 2007

Castle ActiveRecord class with stored procedures

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 that allows us to map :name (or some other named parameter syntax) to the name property of the class. You should notice that NHibernate consistently places the primary key at the end of the parameter list. While it is not perfect, it allows me to meet my requirements to journal all database changes to certain tables.

The code that I submitted is quite simple since I avoided the loader and sql-query mapping elements that would supply Find(primary_key) support. It should theoretically allow stored procedures to be used with any driver and database, although my own testing was limited to SQL Server 2000. It also lacks a critical feature - a working test case. This is the only way that such a feature might reasonably enter the source repository.

The implementation is very easy, and you do not have to provide all of the stored procedures - if you only care about updates, just supply the update attribute ...

insertProc="exec pr_Order_Insert ?, ?, ?",
updateProc="exec pr_Order_Update ?, ?, ?",
deleteProc="exec pr_Order_Delete ?")]
public class Order : ActiveRecordBase

Remember, if you want this patch to be accepted, download it, apply it to your source version of ActiveRecord, build a test case, and vote for it.

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