Rails 3.2.8 引擎中 simple_form 的加载错误

当在 Rails 3.2.8 引擎中加载 simple_form 时，simple_form 初始值设定项文件 simple_form.rb 会导致错误：

/config/initializers/simple_form.rb:2:in `<top (required)>': uninitialized constant SimpleForm (NameError)
        from c:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/engine.rb:588:in `block (2 levels) in <class:Engine>'
        from c:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/engine.rb:587:in `each'

在引擎的 config/initializers 下，simple_form.rb 是：

# Use this setup block to configure all options available in SimpleForm.
SimpleForm.setup do |config|
  # Wrappers are used by the form builder to generate a
  # complete input. You can remove any component from the

The SimpleForm.setup do |config|导致错误。尝试将引擎名称添加为RfqxEmc::SimpleForm.setup do |config|并且错误是相同的。

在 Rails 引擎中安装/加载 simple_form 的正确方法是什么？

这里是post http://blog.jamesalmond.com/using-simple-form-in-an-engine/谈论 Rails 引擎的 simple_form。只需在 simple_form.rb 中添加 require 'simple_form' 即可。