How do I get my rails app to use my postgresql db? - ruby-on-rails-4

Question

I installed prostgres to use with my rails4 app, and I am able to connect to the database server and create databases. Then I made the necessary changes to my Gemfile and config/database.yml to use postgres. Then I created a new app, and in the app I created a User model:
$ rails generate model User name:string email:string
invoke active_record
create db/migrate/20130806145935_create_users.rb
create app/models/user.rb
invoke rspec
create spec/models/user_spec.rb
And then I did:
$ bundle exec rake db:migrate
== CreateUsers: migrating ====================================================
-- create_table(:users)
-> 0.1498s
== CreateUsers: migrated (0.1500s) ===========================================
But in the db directory, I see these files:
development.sqlite3
test.sqlite3
Furthermore, when I try to look at those files with the SQLite Database Browser, I get an error that says they are not sqlite 3 databases. In fact, they are empty:
~/rails_projects/sample_app4_0/db$ ls -al
total 40
drwxr-xr-x 8 7stud staff 272 Aug 6 22:50 .
drwxr-xr-x 24 7stud staff 816 Aug 6 22:23 ..
-rw-r--r-- 1 7stud staff 0 Jul 30 00:21 development.sqlite3
drwxr-xr-x 3 7stud staff 102 Aug 6 22:22 migrate
-rw-r--r-- 1 7stud staff 1063 Aug 6 09:06 schema.rb
-rw-r--r-- 1 7stud staff 343 Jul 29 20:01 seeds.rb
-rw-r--r-- 1 7stud staff 0 Jul 30 03:02 test.sqlite3
I read that you can create your rails app with a flag that tells it to use postgres:
rails new myapp --database postgresql
but I already created my app. Do I have to start over? I'm using git if that makes a difference.
My Gemfile:
source 'https://rubygems.org'
ruby '2.0.0'
#ruby-gemset=railstutorial_rails_4_0
gem 'rails', '4.0.0'
gem 'bootstrap-sass', '2.3.2.0'
#Added for postgres:
gem 'pg', '0.15.1'
group :development, :test do
#gem 'sqlite3', '1.3.7'
gem 'rspec-rails', '2.13.1'
gem 'guard-rspec', '2.5.0'
gem 'spork-rails', github: 'sporkrb/spork-rails'
gem 'guard-spork', '1.5.0'
gem 'childprocess', '0.3.6'
end
group :test do
gem 'selenium-webdriver', '2.0.0'
gem 'capybara', '2.1.0'
gem 'growl', '1.0.3'
end
gem 'sass-rails', '4.0.0'
gem 'uglifier', '2.1.1'
gem 'coffee-rails', '4.0.0'
gem 'jquery-rails', '2.2.1'
gem 'turbolinks', '1.1.1'
gem 'jbuilder', '1.0.2'
group :doc do
gem 'sdoc', '0.3.20', require: false
end
group :production do
#gem 'pg', '0.15.1'
gem 'rails_12factor', '0.0.2'
end
config/database.yml:
development:
adapter: postgresql
encoding: utf8
database: sampleapp_dev #can be anything unique
pool: 5
timeout: 5000
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
adapter: postgresql
encoding: utf8
database: sampleapp_test #can be anything unique
pool: 5
timeout: 5000
production:
adapter: postgresql
database: sampleapp_prod
pool: 5
timeout: 5000

Answer 1

Okay, to figure out what's going on I created a new test app using the --database flag:
rails_projects$ rails new test_postgres --database postgresql
It turns out, all that does is set up your config/database.yml file like this:
development:
adapter: postgresql
encoding: unicode
database: test_postgres_development
pool: 5
username: test_postgres
password:
test:
adapter: postgresql
encoding: unicode
database: test_postgres_test
pool: 5
username: test_postgres
password:
production:
adapter: postgresql
encoding: unicode
database: test_postgres_production
pool: 5
username: test_postgres
password:
And the empty sqlite files:
development.sqlite3
test.sqlite3
were still present in the db directory.
Then I started up postgres, and I used pgAdmin3 to connect to the postgres database server. (If that is confusing, see: How do I start enterpiseDB PostgreSQL on Mac OSX 10.6.8?)
Then I created a model:
~/rails_projects$ cd test_postgres/
~/rails_projects/test_postgres$ rails g scaffold Post title:string author:string body:text
invoke active_record
create db/migrate/20130807061320_create_posts.rb
create app/models/post.rb
invoke test_unit
create test/models/post_test.rb
create test/fixtures/posts.yml
invoke resource_route
route resources :posts
invoke scaffold_controller
create app/controllers/posts_controller.rb
invoke erb
create app/views/posts
create app/views/posts/index.html.erb
create app/views/posts/edit.html.erb
create app/views/posts/show.html.erb
create app/views/posts/new.html.erb
create app/views/posts/_form.html.erb
invoke test_unit
create test/controllers/posts_controller_test.rb
invoke helper
create app/helpers/posts_helper.rb
invoke test_unit
create test/helpers/posts_helper_test.rb
invoke jbuilder
create app/views/posts/index.json.jbuilder
create app/views/posts/show.json.jbuilder
invoke assets
invoke coffee
create app/assets/javascripts/posts.js.coffee
invoke scss
create app/assets/stylesheets/posts.css.scss
invoke scss
create app/assets/stylesheets/scaffolds.css.scss
Then I tried to execute the migration:
~/rails_projects/test_postgres$ bundle exec rake db:migrate
rake aborted!
FATAL: role "test_postgres" does not exist
...
...
That error occured because I don't have a database user(or role in postgres speak) named test_postgres--and it's likely no one else will either. When I set up postgres, I created the user 7stud, which is my Mac user name. To fix that rails error, I just changed the username to 7stud on the three lines in config/database.yml. Edit: in fact, I didn't even need to do that. Because I am the user 7stud on my Mac, that means I am executing my rails commands as 7stud, and coupled with the fact that my postgres db was setup with a user named 7stud, that allows me to completely eliminate the username line in config/database.yml:
development:
adapter: postgresql
encoding: unicode
database: test_postgres_development
pool: 5
test:
adapter: postgresql
encoding: unicode
database: test_postgres_test
pool: 5
production:
adapter: postgresql
encoding: unicode
database: test_postgres_production
pool: 5
Then I tried executing the migration again:
~/rails_projects/test_postgres$ bundle exec rake db:migrate
rake aborted!
FATAL: database "test_postgres_development" does not exist
...
...
Notice that the database.yml file specifies three database names. So I created the development and test databases:
~$ cd /Library/PostgreSQL/9.2/
/Library/PostgreSQL/9.2$ sudo su postgres
Password: <normal sudo password>
bash-3.2$ createdb -O7stud -Eutf8 test_postgres_development
bash-3.2$ createdb -O7stud -Eutf8 test_postgres_test
-O owner
-E encoding
Then I tried executing the migration again:
~/rails_projects/test_postgres$ bundle exec rake db:migrate
== CreatePosts: migrating ====================================================
-- create_table(:posts)
-> 0.0441s
== CreatePosts: migrated (0.0443s) ===========================================
Success (but elsewhere on the net examples show different output with 'Notice' lines).
Then I started a server:
~/rails_projects/test_postgres$ rails s
...and in my browser I entered the url:
http://localhost:3000/posts
...and I created a couple of Posts.
Then using pgAdmin3, I tried to find the posts in the test_postgres_development database. First, I refreshed the 'Databases(3)' line in pgAdmin3 by right clicking on the line and choosing 'Refresh'. Then I searched through the test_postgres_development directory for a long time, with no luck. Under Schemas, I could see a Tables directory that contained a posts directory, so the table got created, but I couldn't figure out how to see if there were any entries in the table. It turns out, you have to right click on the posts directory, then select 'View Data', and voila there were the posts I created.
Or you can view the entries using the command line:
~$ cd /Library/PostgreSQL/9.2/
/Library/PostgreSQL/9.2$ sudo su postgres
Password: <normal sudo password>
bash-3.2$ psql -U 7stud test_postgres_development
psql (9.2.4)
Type "help" for help.
test_postgres_development=> \dt
List of relations
Schema | Name | Type | Owner
--------+-------------------+-------+-------
public | posts | table | 7stud
public | schema_migrations | table | 7stud
(2 rows)
test_postgres_development=> \d posts
Table "public.posts"
Column | Type | Modifiers
------------+-----------------------------+----------------------------------------------------
id | integer | not null default nextval('posts_id_seq'::regclass)
title | character varying(255) |
author | character varying(255) |
body | text |
created_at | timestamp without time zone |
updated_at | timestamp without time zone |
Indexes:
"posts_pkey" PRIMARY KEY, btree (id)
test_postgres_development=> select id, title, author, created_at from posts;
id | title | author | created_at
----+------------------------+--------------+----------------------------
1 | Hi there. | Tom | 2013-08-07 06:24:57.806237
2 | Ola! | Nancy | 2013-08-07 06:25:23.989643
(2 rows)
test_postgres_development=>