Installing PostgreSQL with Ruby on Rails on Mac OS X

I have everything installed. But when I run "rake db:create", I get the following:

Ken-Vogts-MacBook:sixmonths ken$ rake db:create
(in /Users/ken/sixmonths)
rake aborted!
no such file to load -- pg

Here is my database.yml:

development:
  adapter: postgresql
  encoding: unicode
  database: sixmonths_development
  pool: 5
  username: postgres
  password: xxxxxxxx

test:
    adapter: postgresql
    encoding: unicode
    database: sixmonths_test
    pool: 5
    username: sixmonths
    password: xxxxxxxx

production:
    adapter: postgresql
    encoding: unicode
    database: sixmonths_production
    pool: 5
    username: sixmonths
    password: xxxxxxxx

I can see pg is installed when I run: gem list

I tried replacing "postgresql" with "pg" per another post on stackoverflow, but it resulted in this:

Ken-Vogts开发者_运维问答-MacBook:sixmonths ken$ rake db:create
(in /Users/ken/sixmonths)

Seems cool, right?

Nope. Next, I try "rake db:schema:dump" and I get this:

Ken-Vogts-MacBook:sixmonths ken$ rake db:schema:dump
(in /Users/ken/sixmonths)
rake aborted!
Please install the pg adapter: `gem install activerecord-pg-adapter` (no such file to load -- active_record/connection_adapters/pg_adapter)

Of course there is no "activerecord-pg-adapter". What do I have to do to make this work?

Gemfile Contents:

source 'rubygems.org'
gem 'rails', '3.0.0' 
# Bundle edge Rails instead: 
# gem 'rails', :git => 'git://github.com/rails/rails.git' 
gem 'sqlite3-ruby', :require => 'sqlite3' 
# gem 'unicorn' 
# gem 'capistrano'
# gem 'ruby-debug'
# Bundle the extra gems: 
# gem 'bj' 
# gem 'nokogiri' 
# gem 'sqlite3-ruby', :require => 'sqlite3' 
# gem 'aws-s3', :require => 'aws/s3' 
# Bundle gems for the local environment. Make sure to 
# put test-only gems in this group so their generators 
# and rake tasks are available in development mode: 
# group :development, :test do 
  # gem 'webrat' 
# end

Rails 3 will only let you access the gems you specify in your Gemfile, so even if you have it installed in your system-wide gems by doing a gem install pg, it won't be able to find it.

Add gem 'pg' to your Gemfile, run bundle install, and you should be good to go.

I tried many things that I saw as solutions elsewhere, but the only thing that worked for me was replacing

gem 'sqlite3'

with

gem 'pg'

in Gemfile. My database.yml looks the same as yours.

Now both >rake db:create and >rake db:migrate work.

This is on OSX Snow Lepoard, Rails 3.0.7, Postgres 9.0.

And the output from:

gem list --local

is

pg (0.11.0)
polyglot (0.3.1)
postgres-pr (0.6.3)
rack (1.2.2, 1.0.1)
rack-mount (0.7.2, 0.7.1, 0.6.14)
rack-test (0.6.0, 0.5.7)
rails (3.0.7, 3.0.5, 2.3.5, 2.2.2, 1.2.6)