Rails: No connection pool for ActiveRecord::Base

Question

I\'m trying to use rails 4.2.6 to develop an app. I\'m trying to use postgres for database. Server starts fine but when I try loading a page it throws this \"No connection p

Answer 1

In my case, the config/database.yml was taking variables from the environment:

# ...
test:
  <<: *default
  database: <%= ENV.fetch("DB_NAME") %>_test
  username: <%= ENV.fetch("DB_USER") %>
  password: <%= ENV.fetch("DB_PASS") %>
# ...

The error was coming when the new terminal window where I was running the bundle exec rails spec did not have those variables initialized.

Doing,

$ export DB_NAME=mydb
$ export DB_USER=myuser
$ export DB_PASS=mypass
$ bundle exec rails spec

fixed the issue.

Answer 2

For PostgreSQL your database.yml file should look something like that:

default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see rails configuration guide
  # http://guides.rubyonrails.org/configuring.html#database-pooling
  pool: 5

development:
  <<: *default
  database: your_db_name

Also make sure that you have the gem installed: in your Gemfile:

gem 'pg'

Finally, restart your server.

Hope that helps

Edit: I almost forgot, make sure you have your PostgresSQL running, check this link for download and setup.

Answer 3

I've encountered the same problem when I try to access the Model before creating the DataBase.

Make sure you run rake db:migrate at least once.

If you already run migration then check the Database as mentioned in previous answers.