Question

I’m considering using Sequel for some of my hairier SQL that I find too hard to craft in Active Record.

Are there any things I need to be aware of when using Sequel and ActiveRecord on the same project? (Besides the obvious ones like no AR validations in sequel etc…)

Answer 1

Disclaimer: I’m the Sequel maintainer.

Sequel is easy to use along side of or instead of ActiveRecord when using Rails. You do have to setup the database connection manually, but other than that, the usage is similar. Your Sequel model files go in app/models and work similarly to ActiveRecord models.

Setting up the database connections isn’t tedious, it’s generally one line in environment.rb to require sequel, and a line in each environment file (development.rb, test.rb, production.rb) to do something like:

DB = Sequel.connect(…)

So it’s only tedious if you consider 4 lines of setup code tedious.

Using raw SQL generally isn’t a problem unless you are targeting multiple databases. The main reason to avoid it is the increased verbosity. Sequel supports using raw SQL at least as easily as ActiveRecord, but the times where you need to use raw SQL are generally fairly rare in Sequel.

BTW, Sequel ships with multiple validation plugins. The validation_class_methods plugin is similar to ActiveRecord validations, using class methods. The validation_helpers plugin has a simpler implementation using instance level methods, but both can do roughly the same thing.

Finally, I’ll say that if you already have working ActiveRecord code that does what you want, it’s probably not worth the effort to port the code to Sequel unless you plan on adding features.