On 28 Apr 2011, at 20:42, Joel VanderWerf wrote:
>=20
> 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.

>=20
> 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.

>=20
> 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.
>=20
> 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:
>=20
> http://cheat.errtheblog.com/s/sequel
>=20
> The documentation for datasets:
>=20
> http://sequel.rubyforge.org/rdoc/files/doc/dataset_basics_rdoc.html
>=20
>=20
> More on sequel's differences from AR:
>=20
> 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=