向 FormBuilder 添加一个方法，该方法调用呈现部分的辅助方法

所以我有这个辅助方法，对吧？

def table_form_field(name_or_options = nil, *args, &block)
  # ...
  render :partial => "snippets/table_form_field", :locals => options
end

这很好，除了有时我想将它与表单生成器一起使用， 为此，我必须这样称呼它：

table_form_field(:foo, :form_builder => f) do |name|
  f.text_field name
end

必须手动指定 :form_builder 很烦人。所以我的目标是延长ActionView::Helpers::FormBuilder并向其中添加一个新方法，如下所示：

class ActionView::Helpers::FormBuilder
  def table_form_field(name_or_options, options, &block)
    if name_or_options.is_a?(Hash)
      name_or_options[:form_builder] = self
    else
      options[:form_builder] = self
    end

    # But... how can I call the helper?
    # Hmm, I'll try this:

    klass = Class.new do
      include ApplicationHelper
    end

    klass.new.send(:table_form_field, name_or_options, options, &block)

    # Thank you, Mario, but your princess is in another castle!
    #
    # Basically, this tries to call render, and for obvious
    # reasons, klass doesn't know how to render.
    #
    # So... what do I do?
  end
end

您可以访问名为的实例变量@template从表单构建器中，这样你就可以调用table_form_field on the @template多变的。

例如，我将创建一个继承自 ActionView::Helpers::FormBuilder 的自定义表单生成器

class MyFormBuilder < ActionView::Helpers::FormBuilder
  def table_form_field(*attrs, &block)
    @template.table_form_field(*attrs, &block)
  end
end

然后在你的 form_for 中你可以告诉它使用你的自定义表单生成器

<%= form_for @myobject, :builder => MyFormBuilder do |f| %>
  <%= f.table_form_field :myfield do %>
  <% end %>
<%= end %>