在heroku上的rails 4 app中未初始化的常量Moped :: BSON

Question

我刚刚从rails 3更新到rails 4.一切都在本地工作，但部署在heroku上，我收到以下错误：

ActionView::Template::Error (uninitialized constant Moped::BSON):
3: %nav.navbar-collapse
4:   %ul.nav
5:     %li
6:       - if user_signed_in?
7:         = link_to 'Logout', destroy_user_session_path, :method=>'delete'
8:       - else
9:         = link_to 'Login', new_user_session_path
app/views/layouts/_navigation.html.haml:6:in `_app_views_layouts__navigation_html_haml___1118031947301940708_70104067139880'
app/views/layouts/application.html.haml:18:in `_app_views_layouts_application_html_haml__1093647294459268715_70104069850820'

访问current_user时，其他haml文件中也会出现同样的错误 - 如果是current_user   ...

Answer 1

以下对我有用：

添加到Gemfile：

gem "bson"
gem "moped", github: "mongoid/moped"

捆绑安装

添加到application.rb：

require "bson"
require "moped"
Moped::BSON = BSON

回答： https://github.com/mongoid/mongoid/issues/3455

Answer 2

从Moped的作者看Moped 2.0.0的评论（截至本文撰写时，该版本用作mongoid 4.0.0中的驱动程序）：

Moped's BSON implementation has been removed in favor of the 10gen bson gem 2.0 and higher. All Moped::BSON references should be changed to just BSON.

https://github.com/mongoid/moped/blob/master/CHANGELOG.md

Answer 3

在序列化cookie /会话中引用Moped::BSON也可能导致此错误。删除cookie会修复它。