!!Model
class User < ActiveRecord::Base
  has_many :events, :through => :attendees

  validates_presence_of :email, :name, :password
  validates_uniqueness_of :email

  attr_accessor :password
  attr_accessible :name, :password
end

!!Controller
class LoginController < ApplicationController

  def add_user
    if request.get?
      @user = User.new
    else
      @user = User.new(params[:user])
      if @user.save!
        flash[:notice] = "User #{@user.name} created"
        redirect_to(:action => "login")
      end
    end
  end
end

!!View
<h1>New user</h1>

<% form_tag do %>
<table>
  <tr>
    <td>e-mail address:</td>
    <td><%= text_field("user", "email") %></td>
  </tr>
  <tr>
    <td>Name:</td>
    <td><%= text_field("user", "name") %></td>
  </tr>
  <tr>
    <td>Password:</td>
    <td><%= password_field("user", "password") %></td>
  </tr>
  <tr>
    <td></td>
    <td><input type="submit" value="Register" /></td>
  </tr>
</table>
<% end %>

!!Output on submit, all fields completed
 ActiveRecord::RecordInvalid in LoginController#add_user

Validation failed: Email can't be blank

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

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/validations.rb:764:in `save_without_transactions!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/connection_adapters/abstract/database_statements.rb:59:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:95:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:121:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
#{RAILS_ROOT}/app/controllers/login_controller.rb:8:in `add_user'

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/validations.rb:764:in `save_without_transactions!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/connection_adapters/abstract/database_statements.rb:59:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:95:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:121:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:1095:in `send'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:1095:in `perform_action_without_filters'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:632:in `call_filter'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:619:in `perform_action_without_benchmark'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
c:/ruby/lib/ruby/1.8/benchmark.rb:293:in `measure'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/rescue.rb:83:in `perform_action'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:430:in `send'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:430:in `process_without_filters'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:624:in `process_without_session_management_support'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/session_management.rb:114:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:330:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/dispatcher.rb:41:in `dispatch'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel/rails.rb:73:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:551:in `process_client'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:550:in `each'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:550:in `process_client'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `initialize'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `new'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `initialize'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `new'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:956:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:955:in `each'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:955:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/bin/mongrel_rails:127:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel/command.rb:199:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/bin/mongrel_rails:235
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/commands/servers/mongrel.rb:60
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/commands/server.rb:39
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
script/server:3

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/validations.rb:764:in `save_without_transactions!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/connection_adapters/abstract/database_statements.rb:59:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:95:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:121:in `transaction'
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.1/lib/active_record/transactions.rb:133:in `save!'
#{RAILS_ROOT}/app/controllers/login_controller.rb:8:in `add_user'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:1095:in `send'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:1095:in `perform_action_without_filters'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:632:in `call_filter'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:619:in `perform_action_without_benchmark'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
c:/ruby/lib/ruby/1.8/benchmark.rb:293:in `measure'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/benchmarking.rb:66:in `perform_action_without_rescue'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/rescue.rb:83:in `perform_action'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:430:in `send'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:430:in `process_without_filters'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/filters.rb:624:in `process_without_session_management_support'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/session_management.rb:114:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.1/lib/action_controller/base.rb:330:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/dispatcher.rb:41:in `dispatch'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel/rails.rb:73:in `process'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:551:in `process_client'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:550:in `each'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:550:in `process_client'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `initialize'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `new'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:636:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `initialize'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `new'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:625:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:956:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:955:in `each'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel.rb:955:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/bin/mongrel_rails:127:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/lib/mongrel/command.rb:199:in `run'
c:/ruby/lib/ruby/gems/1.8/gems/mongrel-0.3.13.3-mswin32/bin/mongrel_rails:235
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:489:in `load'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/commands/servers/mongrel.rb:60
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.1/lib/commands/server.rb:39
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:343:in `new_constants_in'
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.0/lib/active_support/dependencies.rb:496:in `require'
script/server:3

Request

Parameters: {"user"=>{"name"=>"Merlin83b", "password"=>"password", "email"=>"example@example.com"}}

Show session dump

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


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