From: Iain Barnett <iainspeed@...>
Date: 2011-04-29T06:16:51+09:00
Subject: Re: Best gem for an existing mysql database


On 28 Apr 2011, at 20:42, Joel VanderWerf wrote:
> 
> Another factor to consider, when the database precedes the app, is whether the ORM layer supports the schema. IIUC, AR doesn't support composite primary keys without using an extra library. Sequel does support composite primary keys (this was very helpful to my team just in the last few weeks). This difference may not matter much, but it's something to be aware of.

This is a deal breaker, or maker in this case as the database does hold several composite keys.

> 
> Rather than use models, I often find it easier to think in relational terms and code in ruby, and that's what sequel's datasets let you do.

I think this would suit my style of thinking too. I'm quite comfortable with SQL and sets and they seem to make more sense for a lot of problems than starting with objects, for me anyway.

> 
> Sequel and AR will both let you drop to the SQL level, if the model level isn't quite right for what you want to do. I don't know about DataMapper or other ORMs.
> 
> One thing I've always liked about sequel is that there is an intermediate level, between models and SQL: datasets with their chained query methods. Some examples:
> 
> http://cheat.errtheblog.com/s/sequel
> 
> The documentation for datasets:
> 
> http://sequel.rubyforge.org/rdoc/files/doc/dataset_basics_rdoc.html
> 
> 
> More on sequel's differences from AR:
> 
> http://sequel.rubyforge.org/rdoc/files/doc/active_record_rdoc.html

Thanks, I'll give those a look. I really appreciate the time you've taken to give me a good answer, it's difficult to tell from just reading the docs / looking at examples, as they all *seem* to do what you want, and right now I don't have the time to get far down the road before failing.

Thanks again.

Regards,
Iain