Can't get a simple application to work with Rails 2.0...

Clearly I'm doing something wrong, but should it really be this
difficult to figure out?

I found the Rails 2.0 tutorial movie and did the following:

rails ESPlanner_Web --d=mysql

Edited database.yml appropriately

script/generate scaffold users Username:string Password:String

Tweaked the migrations to get the lengths right and added an index.

rake db:migrate

Checked via phpmyadmin that the tables got set up properly (they did).

Modified routes.rb to start at the users controller.
Deleted public/index.html.


Hit localhost:3000 using Firefox and get:

NameError in Users#index

Showing users/index.html.erb where line #22 raised:

undefined local variable or method `new_users_path' for

Extracted source (around line #22):

20: <br />
22: <%= link_to 'New users', new_users_path %>

By which I assume that the index method of the Users controller didn't
define new_users_path so I looked at that and see:

  def index
    @users = Users.find(:all)

    respond_to do |format|
      format.html # index.html.erb
      format.xml { render :xml => @users }

presumably the format.html statement is magic that hits index.html.erb
which requires new_users_path to be defined but it isn't.

Am I doing something wrong or is the scaffold generator broken?


Dick Munroe

The problem is in your routes.rb file. Somewhere, you have nullified this command:

map.resources :users

I can’t tell without seeing your routes file, but you will want to ensure that that line exists in that file. Feel free to paste your entire routes.rb file here so we can look at it. The new_users_path method is defined by that single line in routes.rb.

Also, to save you possible trouble in the future, table names and column names are not uppercased. Uppercased things in Ruby mean that they are Constants! (I noticed your scaffold command had the field names with capital letters so that’s why I brought it up.)

Well, the routes file (with the exception of the map.root is generated
by rails. Here it is:

ActionController::Routing::Routes.draw do |map|
  map.resources :families

  map.resources :users

  # The priority is based upon order of creation: first created ->
highest priority.

  # Sample of regular route:
  # map.connect 'products/:id', :controller => 'catalog', :action =>
  # Keep in mind you can assign values other than :controller
and :action

  # Sample of named route:
  # map.purchase 'products/:id/purchase', :controller =>
'catalog', :action => 'purchase'
  # This route can be invoked with purchase_url(:id =>

  # Sample resource route with options:
  # map.resources :products, :member => { :short => :get, :toggle
=> :post }, :collection => { :sold => :get }

  # Sample resource route with sub-resources:
  # map.resources :products, :has_many =>
[ :comments, :sales ], :has_one => :seller

  # Sample resource route within a namespace:
  # map.namespace :admin do |admin|
  # # Directs /admin/products/* to Admin::ProductsController (app/
  # admin.resources :products
  # end

  # You can have the root of your site routed with map.root -- just
remember to delete public/index.html.
  map.root :controller => "users"

  # See how all your routes lay out with "rake routes"

  # Install the default routes as the lowest priority.
  map.connect ':controller/:action/:id'
  map.connect ':controller/:action/:id.:format'

When I do a rake routes I get:

             families GET /families
{:controller=>"families", :action=>"index"}
   formatted_families GET /families.:format
{:controller=>"families", :action=>"index"}
                      POST /families
{:controller=>"families", :action=>"create"}
                      POST /families.:format
{:controller=>"families", :action=>"create"}
           new_family GET /families/new
{:controller=>"families", :action=>"new"}
formatted_new_family GET /families/new.:format
{:controller=>"families", :action=>"new"}
          edit_family GET /families/:id/edit
{:controller=>"families", :action=>"edit"}
formatted_edit_family GET /families/:id/edit.:format
{:controller=>"families", :action=>"edit"}
               family GET /families/:id
{:controller=>"families", :action=>"show"}
     formatted_family GET /families/:id.:format
{:controller=>"families", :action=>"show"}
                      PUT /families/:id
{:controller=>"families", :action=>"update"}
                      PUT /families/:id.:format
{:controller=>"families", :action=>"update"}
                      DELETE /families/:id
{:controller=>"families", :action=>"destroy"}
                      DELETE /families/:id.:format
{:controller=>"families", :action=>"destroy"}
                users GET /users
{:controller=>"users", :action=>"index"}
      formatted_users GET /users.:format
{:controller=>"users", :action=>"index"}
                      POST /users
{:controller=>"users", :action=>"create"}
                      POST /users.:format
{:controller=>"users", :action=>"create"}
             new_user GET /users/new
{:controller=>"users", :action=>"new"}
   formatted_new_user GET /users/new.:format
{:controller=>"users", :action=>"new"}
            edit_user GET /users/:id/edit
{:controller=>"users", :action=>"edit"}
  formatted_edit_user GET /users/:id/edit.:format
{:controller=>"users", :action=>"edit"}
                 user GET /users/:id
{:controller=>"users", :action=>"show"}
       formatted_user GET /users/:id.:format
{:controller=>"users", :action=>"show"}
                      PUT /users/:id
{:controller=>"users", :action=>"update"}
                      PUT /users/:id.:format
{:controller=>"users", :action=>"update"}
                      DELETE /users/:id
{:controller=>"users", :action=>"destroy"}
                      DELETE /users/:id.:format
{:controller=>"users", :action=>"destroy"}
                 root /
{:controller=>"users", :action=>"index"}

Boy, I wish there was some documentation of what's going on here...

Thanks for any help


After doing a little digging in the Agile Web Development book, it
looks like the helpers for the views aren't being defined. I looked
in app/helpers/users_helper.rb and find:

module UsersHelper

Should rails have defined a bunch of helpers here? or does that get
done dynamically by the map.resources in routes.db?


Dick Munroe

:slight_smile: No. The helpers you’re looking for are defined automatically by the map.resources stuff in routes.rb, which you yourself verified in the rake task.





That will work. (note the singular form… didn’t notice that myself until I reread your original message.) Now, I can’t believe that the generator would get that wrong. Did you modify it by any chance?

If you’re sure you didn’t, try creating a brand new app doing the same thing. It should just work.

And that appears to be at least part of the problem. When I define a
helper of the form:

  def new_users_path

at least I can get the page displayed.

Is this a bug in rails scaffolding? or did I do something wrong when I
generated the scaffold?


Dick Munroe

I don’t believe there is. I just generated a new app from scratch and all of the pages were created as expected. new_users_path is not a valid route name. new_user_path is.

How did you geneerate your scaffold?

Correct command should be ruby script/generate user username:string password:string

If you did ruby script/generate users (note the plural) I could see that happening.

You most certainly do NOT need to have your own helper.

Yeah, it turns out that using the plural form when I generated the
scaffold was the problem. I didn't see anything in the Agile
Development book about plurals versus non-plurals so that got me.

Lots of under the hood stuff going on here.

Thanks for the help

Dick Munroe

The book uses the rails 1.x version of scaffolding. IF you have Rails 2.0 installed then there’s going to be a LOT of stuff that doesn’t work for you.