我的应用程序有一个用户模型，包括一个“新手”布尔属性。我在注册页面中制作了一个单选按钮，让新用户选择他是否是“新手”。
<%= f.radio_button :newbie, true %> <%= f.label :newbie, "I'm a newbie" %>
<%= f.radio_button :newbie, false%> <%= f.label :newbie, "I'm not a newbie" %>
该应用程序在本地服务器上运行良好。但是部署到heroku后，我无法访问注册页面。heroku 日志显示：
2012-04-29T20:16:16+00:00 app[web.1]: Started GET "/signup" for 72.181.169.183 at 2012-04-29 20:16:16 +0000
2012-04-29T20:16:16+00:00 app[web.1]: Processing by UsersController#new as HTML
2012-04-29T20:16:16+00:00 app[web.1]: Rendered shared/_error_messages.html.erb (0.0ms)
2012-04-29T20:16:16+00:00 app[web.1]: Rendered users/new.html.erb within layouts/application (1.3ms)
2012-04-29T20:16:16+00:00 app[web.1]: Completed 500 Internal Server Error in 2ms
2012-04-29T20:16:16+00:00 app[web.1]:
2012-04-29T20:16:16+00:00 app[web.1]: ActionView::Template::Error (undefined method `newbie' for #<User:0x00000004d21280>):
2012-04-29T20:16:16+00:00 app[web.1]: 6: <%= form_for(@user) do |f| %>
2012-04-29T20:16:16+00:00 app[web.1]: 7: <%= render 'shared/error_messages', object: f.object %>
2012-04-29T20:16:16+00:00 app[web.1]: 8:
2012-04-29T20:16:16+00:00 app[web.1]: 10: <%= f.radio_button :newbie, false%> <%= f.label :newbie, "I'm not a newbie" %>
2012-04-29T20:16:16+00:00 app[web.1]: 9: <%= f.radio_button :newbie, true %> <%= f.label :newbie, "I'm a newbie" %>
2012-04-29T20:16:16+00:00 app[web.1]: 11:
2012-04-29T20:16:16+00:00 app[web.1]: app/views/users/new.html.erb:9:in `block in _app_views_users_new_html_erb___587113142513507349_39337120'
2012-04-29T20:16:16+00:00 app[web.1]: 12: <%= f.label :name %>
2012-04-29T20:16:16+00:00 app[web.1]: app/views/users/new.html.erb:6:in `_app_views_users_new_html_erb___587113142513507349_39337120'
我已经运行了迁移，我可以看到新手已成功迁移
Migrating to AddRoleToUsers (20120425182820)
== AddRoleToUsers: migrating =================================================
-- add_column(:users, :newbie, :boolean)
-> 0.0023s
== AddRoleToUsers: migrated (0.0024s) ========================================
可能是什么问题呢？
谢谢