title: Rails 5 and MongoDB: Specified 'sqlite3' for database adapter, but the gem is not loaded
body: <p>I am trying to set up MongoDB with Rails 5. I'm using Cloud9 which seems to automatically set you up to use SQLite, so I'm having some problems with that. I have installed MongoDB and added it to my gem file.</p>
  
  <p>When I run</p>
  
  <pre><code>rails g mongoid:config
  </code></pre>
  
  <p>I get the error:</p>
  
  <blockquote>
    <p>Specified 'sqlite3' for database adapter, but the gem is not loaded. Add <code>gem 'sqlite3'</code> to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)</p>
  </blockquote>
  
  <p>Here is database.yml</p>
  
  <pre><code># SQLite version 3.x
  #   gem install sqlite3
  #
  #   Ensure the SQLite 3 gem is defined in your Gemfile
  #   gem 'sqlite3'
  #
  default: &amp;default
    adapter: sqlite3
    pool: 5
    timeout: 5000
  
  development:
    &lt;&lt;: *default
    database: db/development.sqlite3
  
  # 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:
    &lt;&lt;: *default
    database: db/test.sqlite3
  
  production:
    &lt;&lt;: *default
    database: db/production.sqlite3
  </code></pre>
  
  <p>I'm not sure how to re-write this for MongoDB? I think I also need to remove or disable ActiveRecord but I'm not sure how to do this in Rails 5.</p>