`method_missing': undefined method `devise' for User (call 'User.connection' to establish a connection)

Question

I am new to Ruby on Rails and am trying to make my first application. I am having issues though anytime I run any rails generate command. I get the following er

Answer 1

rails g devise install != rails g devise:install

I ran into this problem as well. Executing rails generate devise install (sic!) there was nothing that seemed not to have worked. The terminal output was:

$ rails g devise install
  Running via Spring preloader in process 5422
      invoke  active_record
      create    db/migrate/20180306165306_devise_create_installs.rb
      create    app/models/install.rb
      insert    app/models/install.rb
       route  devise_for :installs

But I missed the semicolon. Reverting these changes and then executing rails generate devise:install (note the : between devise and install), everything worked out perfectly. Also you get a much more extensive output:

$ rails g devise:install
  Running via Spring preloader in process 5218
      create  config/initializers/devise.rb
      create  config/locales/devise.en.yml
  ===============================================================================

  Some setup you must do manually if you haven't yet:

    1. Ensure you have defined default url options in your environments files. Here
       is an example of default_url_options appropriate for a development environment
       in config/environments/development.rb:

         config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }

       In production, :host should be set to the actual host of your application.

    2. Ensure you have defined root_url to *something* in your config/routes.rb.
       For example:

         root to: "home#index"

    3. Ensure you have flash messages in app/views/layouts/application.html.erb.
       For example:

         
<%= notice %>
         
<%= alert %>

    4. You can copy Devise views (for customization) to your app by running:

         rails g devise:views

  ===============================================================================