Is Ruby on Rails (jruby) not so good for existing databases?

Question

I'm learning Ruby on Rails and doing the contactlist thing, 20 minute blog and so on, but I am concerned about using RoR with existing non-MySQL databases. I know RoR can communicate with non-MySQL; in fact, I am using jRuby on Rails so I can use JDBC.

My question is how RoR works with existing database. Do I lose all the benefit of using RoR when I'm using existing databases? I don't want to always genearate updates and what not. I have to be careful of that as it is very senstive. I just feel like learning all this framework "stuff" may be for naught because the majority of what I will be doing is not a new database and all the "fancy" stuff RoR does will not even make sense for me. And I absolutely cannot change the data to another databases. I have many different databases to hit and bring back in one webpage.

FWIW, I am used asp.net (non-MVC), table adapters, and ODBC (all intranet), but am not on a Microsoft server at the moment. I am on Mac OS X Server 10.5.7, jruby, jdbc, ror.

Am I using the wrong framework for what I need? I can easily see PHP working like Classic ASP, but I cannot yet picture this for RoR and I do not want to use php, if I don't have to. JSP and the J2EE stack is a possibility.

Thank you.

EDIT: Is there any advantage to using RoR in this context? I asked this to the Django folks a year of so ago and was just told that maybe it wasn't good for legacy data. I don't want to make it work like a round peg in a square hole just so I can say I'm using RoR and ruby. Would I better off with j2ee, hibernate in this?

EDIT: Is J2EE and MVC the better way to go for what I have described?

Answer 1

It works, but you have to do a lot more work to make things happen.

The usual pain points when you're using an existing schema with ActiveRecord / Rails are:

• table names
• foreign key names
• primary keys (especially composite primary keys)

ActiveRecord makes a whole bunch of assumptions about how you have things set up. There are overrides in a lot of cases, but not everything. You can usually get most of the way there unless you're doing weird things in your table structure to start with.