What ORM to use in one process multiple db connect

问题:

Checked ActiveRecord, DataMapper, Sequel: some use globals (static variables) some require open db connection before loading source file with models. What ORM is better to use in sinatra application that uses different databases.

回答1:

DataMapper is designed for multi-database use.

You can set up multiple repositories just by saying something like DataMapper.setup(:repository_one, "mysql://localhost/my_db_name").

DataMapper then tracks all the repositories that have been setup in a hash that you can reference and use for scoping:

DataMapper.repository(:repository_one){ MyModel.all }

(The default scope just being DataMapper.repository, which you can set up by saying DataMapper.setup(:default, "postgres://localhost/my_primary_db") or the like)

回答2:

It seems that it is possible to use different databases in most of ORMs. For DataMapper look at knowtheory answer. For Sequel you can pass database handler to model:

class Tag < Sequel::Model(db)
end

where db is opened database. For ActiveRecord you can use establish_connection method.

回答3:

Personally I prefer Sequel for all my ORM and basic database accesses and is what I use with Sinatra/Padrino and any other time I need to access a database outside of Rails.

I've used DataMapper but felt Sequel was easier and more flexible, but maybe that's just how my mind works. ActiveRecord is OK on its own, but I think it works best in combination with Rails.

Which is "better"? I think that is subjective and mostly is tied to how your brain works.