How to handle Ruby on Rails error: "Please install the postgresql adapter: `gem install activerecord-postgresql-adapter'"

Question

Running a Ruby on Rails (RoR) app or Ruby code which uses the ActiveRecord framework, you get the error message:

Please install the postgresql adapter: gem install activerecord-postgresql-adapter

Trying to run:

gem install activerecord-postgresql-adapter

also fails, leaving you at a loss.

Answer 1

If this is on a *nix platform, you probably need to run sudo gem install activerecord-postgresql-adapter

Answer 2

You could read the following post to get an idea.

Answer 3

This means you don’t have the new ‘pg’ postgresql library installed. This is easily fixed with a bit of:

sudo gem install pg

I (Dov) found other solutions on the web which described setting GEM_HOME and adding ~/.gem/ruby/vers/bin to your PATH, but they didn't work. This solution above was provided by Mark Mansour on his blog State of Flux at: http://stateofflux.com/2008/7/13/activerecord-postgresql-adapter-in-rails-2-1/

Answer 4

I did a little roundup of the current state of Ruby + PostgreSQL database drivers on railsonpostgresql.com; I think sudo gem install pg is probably the one you want.

Answer 5

The problem is not what anyone wrote. The problem is that the name of the postgresql database adapter is "postgresql", not "postgres", fix the database.yml, but the name of the GEM is "pg".

Answer 6

sudo apt-get install ruby1.8-dev

then...

gem install pg

Worked for me!