Gem clash: activerecord-jdbc-adapter and pg

Posted by Nick Sieger Thu, 28 Jan 2010 15:16:49 GMT

I got a note from a community member about an annoying problem that a few people have run into when installing activerecord-jdbc-adapter (AR-JDBC) into a C Ruby implementation:

NameError: uninitialized constant

Turns out it’s pretty easy to momentarily forget to use jruby -S gem or jgem and just gem install activerecord-jdbc-adapter and suddenly your pg Postgres gems are not working properly. I thought it was worth documenting here in case others run into this problem.

I apologize for the clash. I had to provide a stub pg.rb in AR-JDBC inside of JRuby so that I could get active_record/connection_adapters/postgresql_adapter.rb to load with a database adapter type of postgresql. Because of load path order issues, I couldn’t get AR-JDBC’s code to load before ActiveRecord’s. At the time I was thinking this wouldn’t be a problem because the pg library won’t work on JRuby anyway, right? Wrong.

I can think of a couple options going forward:

  1. Submit a patch to ActiveRecord so that active_record/connection_adapters/postgresql_adapter.rb can load without requiring pg up front and then AR-JDBC won’t have to stub it out.
  2. Display a big fat warning message when AR-JDBC is installed into anything other than JRuby.

Any other thoughts?

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