Ruby - ActiveRecord::ConnectionNotEstablished

Question

I am rather new to Ruby and have been following along with the book \"Ruby On Rails 3 Tutorial - Learn Ruby by Example - by Michael Hartl\". I am currently in Chapter 3 whic

Answer 1

Update the adapter in config/database.yml file to the database name being used by your application and restart your rails. This will resolve the issue.

For me it got reset to some other DB name, so it was giving error. After updating it to "sqlite3", it worked fine.

Answer 2

Add this to your Gemfile:

gem 'sqlite3-ruby', :require => 'sqlite3'

Answer 3

i am new to it but this might be pretty helpful(if you are in development just check development leave production and test environments):

1. Create a database and give it a name.

2. Open up .config/database.yml

   adapter: mysql2

   database: specify_your_newly_created_database #check if its automatically updated or not

   pool: 5

   username: your designated username.

   password: your designated password.

   host: localhost

3. $ rails server

   => Booting WEBrick

   => Rails 3.2.9 application starting in development on http:// 0. 0. 0 .0 :3000

   => Call with -d to detach

   => Ctrl-C to shutdown server

   [2012-12-12 23:31:50] INFO WEBrick 1.3.1

   [2012-12-12 23:31:50] INFO ruby 1.9.3 (2012-11-10) [i386-mingw32]

   [2012-12-12 23:31:50] INFO WEBrick::HTTPServer#start: pid=4068 port=3000

   Started GET "/demo/index" for 127.0.0.1 at 2012-12-12 23:32:40 +0545

   Connecting to database specified by database.yml

   Processing by DemoController#index as HTML

   Rendered demo/index.html.erb within layouts/application (0.0ms)

   Compiled demo.css (46ms) (pid 4068)

and so on...........

if your'e just trying to solve the ActiceRecord then this will solve the problem and display your first hello page. This is the problem that occurs sometime since rails searches for the database though we have nothing to do with database when dealing with the first hello page, so just check it once if not the we will solve it together. Cheers!

Answer 4

If you have in your Gemfile something like:

gem 'sqlite3-ruby', '> 1.2.0', :require => 'sqlite3'

replace it with:

gem 'sqlite3'

Answer 5

Try updating the sqlite3 gem. bundle update sqlite3

Answer 6

I had the same problem, I started the sample-app from scratch and used this gemfile:

source 'http://rubygems.org'

gem 'rails', '3.1.1'

gem 'sqlite3'

group :development do
  gem 'rspec-rails', '2.6.1'
end


group :test do
  gem 'rspec-rails', '2.6.1'
  gem 'webrat', '0.7.1'
end

group :assets do
  gem 'sass-rails',   '~> 3.1.4'
  gem 'coffee-rails', '~> 3.1.1'
  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

This solved the problem for me :)