NameError in AdminController#index building scaffold

Rails
1

I’m a pretty big newbie with ROR, but when following a tutorial I
encounter an ugly error when building a scaffold. Here is my
environment

Dev system:

  • Windows XP
  • java version “1.5.0_06”
  • MySQL java version “1.5.0_06”
  • Ruby 1.8.4
  • Ruby Gems 0.9.0
  • Gem install mysql
    Successfully installed mysql-2.7.1-mswin32
    Installing ri documentation for mysql-2.7.1-mswin32…
    Installing RDoc documentation for mysql-2.7.1-mswin32…
  • Table in ediweb database
    mysql> desc users;
    ±---------------±------------±-----±----±--------±---------------+
    | Field | Type | Null | Key | Default | Extra |
    ±---------------±------------±-----±----±--------±---------------+
    | user_id | int(11) | NO | PRI | NULL | auto_increment |
    | user_login | varchar(50) | NO | | | |
    | user_firstname | varchar(50) | NO | | | |
    | user_lastname | varchar(50) | NO | | | |
    | user_role | varchar(50) | NO | | | |
    ±---------------±------------±-----±----±--------±---------------+
    5 rows in set (0.18 sec)

I am also connecting to Subversion on a linux system as my Repo.

When I start my server I am able to view several other controllers. I
stop my server and create a scaffold in RadRails.

ediweb> ruby script/generate scaffold Users Admin
exists app/controllers/
exists app/helpers/
exists app/views/admin
exists test/functional/
dependency model
exists app/models/
exists test/unit/
exists test/fixtures/
create app/models/users.rb
create test/unit/users_test.rb
create test/fixtures/users.yml
identical app/views/admin/_form.rhtml
create app/views/admin/list.rhtml
create app/views/admin/show.rhtml
create app/views/admin/new.rhtml
create app/views/admin/edit.rhtml
create app/controllers/admin_controller.rb
create test/functional/admin_controller_test.rb
create app/helpers/admin_helper.rb
create app/views/layouts/admin.rhtml
create public/stylesheets/scaffold.css

Looks like no problem, but then I check the page:

NameError in AdminController#index

uninitialized constant User

RAILS_ROOT: ./script/…/config/…
Application Trace | Framework Trace | Full Trace

D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:123:in
const_missing' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:131:inconst_missing’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/inflector.rb:161:in
constantize' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/core_ext/string/inflections.rb:59:inconstantize’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:194:in
paginator_and_collection_for' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:129:inpaginate’
#{RAILS_ROOT}/app/controllers/admin_controller.rb:12:in list' #{RAILS_ROOT}/app/controllers/admin_controller.rb:3:inindex’
-e:4

D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:123:in
const_missing' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:131:inconst_missing’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/inflector.rb:161:in
constantize' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/core_ext/string/inflections.rb:59:inconstantize’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:194:in
paginator_and_collection_for' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:129:inpaginate’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/base.rb:941:in
perform_action_without_filters' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/filters.rb:368:inperform_action_without_benchmark’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/benchmarking.rb:69:in
perform_action_without_rescue' D:/ruby/lib/ruby/1.8/benchmark.rb:293:inmeasure’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/benchmarking.rb:69:in
perform_action_without_rescue' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/rescue.rb:82:inperform_action’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/base.rb:408:in
process_without_filters' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/filters.rb:377:inprocess_without_session_management_support’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/session_management.rb:117:in
process' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/dispatcher.rb:38:indispatch’
D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:115:in
handle_dispatch' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:81:inservice’
D:/ruby/lib/ruby/1.8/webrick/httpserver.rb:104:in service' D:/ruby/lib/ruby/1.8/webrick/httpserver.rb:65:inrun’
D:/ruby/lib/ruby/1.8/webrick/server.rb:173:in start_thread' D:/ruby/lib/ruby/1.8/webrick/server.rb:162:instart_thread’
D:/ruby/lib/ruby/1.8/webrick/server.rb:95:in start' D:/ruby/lib/ruby/1.8/webrick/server.rb:92:instart’
D:/ruby/lib/ruby/1.8/webrick/server.rb:23:in start' D:/ruby/lib/ruby/1.8/webrick/server.rb:82:instart’
D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:67:in
dispatch' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/commands/servers/webrick.rb:59 D:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:inrequire’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:147:in
require' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/commands/server.rb:30 D:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:inrequire’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:147:in
`require’
script/server:3

D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:123:in
const_missing' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:131:inconst_missing’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/inflector.rb:161:in
constantize' D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/core_ext/string/inflections.rb:59:inconstantize’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:194:in
paginator_and_collection_for' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/pagination.rb:129:inpaginate’
#{RAILS_ROOT}/app/controllers/admin_controller.rb:12:in list' #{RAILS_ROOT}/app/controllers/admin_controller.rb:3:inindex’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/base.rb:941:in
perform_action_without_filters' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/filters.rb:368:inperform_action_without_benchmark’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/benchmarking.rb:69:in
perform_action_without_rescue' D:/ruby/lib/ruby/1.8/benchmark.rb:293:inmeasure’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/benchmarking.rb:69:in
perform_action_without_rescue' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/rescue.rb:82:inperform_action’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/base.rb:408:in
process_without_filters' D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/filters.rb:377:inprocess_without_session_management_support’
D:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/session_management.rb:117:in
process' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/dispatcher.rb:38:indispatch’
D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:115:in
handle_dispatch' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:81:inservice’
D:/ruby/lib/ruby/1.8/webrick/httpserver.rb:104:in service' D:/ruby/lib/ruby/1.8/webrick/httpserver.rb:65:inrun’
D:/ruby/lib/ruby/1.8/webrick/server.rb:173:in start_thread' D:/ruby/lib/ruby/1.8/webrick/server.rb:162:instart_thread’
D:/ruby/lib/ruby/1.8/webrick/server.rb:95:in start' D:/ruby/lib/ruby/1.8/webrick/server.rb:92:instart’
D:/ruby/lib/ruby/1.8/webrick/server.rb:23:in start' D:/ruby/lib/ruby/1.8/webrick/server.rb:82:instart’
D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/webrick_server.rb:67:in
dispatch' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/commands/servers/webrick.rb:59 D:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:inrequire’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:147:in
require' D:/ruby/lib/ruby/gems/1.8/gems/rails-1.1.6/lib/commands/server.rb:30 D:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:inrequire’
D:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:147:in
`require’
script/server:3
-e:4

This error occured while loading the following files:
user.rb

Request

Parameters: None

Show session dump

flash: !map:ActionController::Flash::FlashHash {}

Response
Headers: {“cookie”=>[], “Cache-Control”=>“no-cache”}

I have tried building the scaffold with users and admin instead of Users
and Admin, but it’s still not working! Also, I verified MySQL
connectivity from ruby server to the database by doing the following:

ActiveRecord::Base.connection.select_all(‘desc users’)
=> [{“Extra”=>“auto_increment”, “Default”=>nil, “Null”=>“NO”,
“Type”=>“int(11)”, “Field”=>“user_id”, “Key”=>“PRI”}, {“Extra”=>"",
“Default”=>"", “Null”=>“NO”, “Type”=>“varchar(50)”,
“Field”=>“user_login”, “Key”=>""}, {“Extra”=>"", “Default”=>"",
“Null”=>“NO”, “Type”=>“varchar(50)”, “Field”=>“user_firstname”,
“Key”=>""}, {“Extra”=>"", “Default”=>"", “Null”=>“NO”,
“Type”=>“varchar(50)”, “Field”=>“user_lastname”, “Key”=>""},
{“Extra”=>"", “Default”=>"", “Null”=>“NO”, “Type”=>“varchar(50)”,
“Field”=>“user_role”, “Key”=>""}]

ActiveRecord::Base.connection.select_all(‘select * from users’)
ActiveRecord::Base.connection.select_all(‘select * from users’)
=> []

My question is I do have one record in the table but the ‘select *’
query doesn’t come back with nothing. Any help would be appreciated! :slight_smile:

Thanks
James

2

One more note, I didn’t have any records in the database! When I
inserted some I am still able to connect through the development console
– but still gettig the same error from the http://localhost:3000/admin
— any ideas?

ActiveRecord::Base.connection.select_all(‘select* from users’)
ActiveRecord::Base.connection.select_all(‘select* from users’)
=> [{“user_login”=>“jsmith”, “user_firstname”=>“joe”, “user_id”=>“1”,
“user_role”=>“admin”, “user_lastname”=>“smith”},
{“user_login”=>“bsmith”, “user_firstname”=>“bob”, “user_id”=>“2”,
“user_role”=>“user”, “user_lastname”=>“smith”}]

3

I forgot by database.yml has the following for the dev environment:

development:
adapter: mysql
database: ediweb
username: root
password: ********
host: localhost

4

Also, my model users.rb:

class Users < ActiveRecord::Base
end

5

I was able to solve my own problem. I generated the scaffold using
‘ruby script/generate scaffold user Admin’

ediweb> ruby script/generate scaffold user Admin
exists app/controllers/
exists app/helpers/
exists app/views/admin
exists test/functional/
dependency model
exists app/models/
exists test/unit/
exists test/fixtures/
create app/models/user.rb
create test/unit/user_test.rb
create test/fixtures/users.yml
create app/views/admin/_form.rhtml
create app/views/admin/list.rhtml
create app/views/admin/show.rhtml
create app/views/admin/new.rhtml
create app/views/admin/edit.rhtml
create app/controllers/admin_controller.rb
create test/functional/admin_controller_test.rb
create app/helpers/admin_helper.rb
create app/views/layouts/admin.rhtml
create public/stylesheets/scaffold.css

How did ruby know that my database table was ‘users’ when I generated
the scaffold as ‘user’? I’m sorry if this is a dumb question :slight_smile:

6

Unless you change it, it always looks for the plural form of the
model as the table… so a “person” model would have a “people” table,
“cat” model would have “cats” table, etc. This is pretty basic and
covered in “Agile Web D. in Rails” as well as a lot of
online tutorials.

7

I figured it out – I had to remove the mysql gem.

gem uninstall mysql

Everything worked after that!