Rails的未定义局部变量或方法错误

Question

I have a method in controller -

def undo_link
  view_context.link_to("undo", revert_version_path(@page.versions.scoped.last), :method => :post)
end

But when i call it in views with "#{undo_link}" . I get the undefined local variable or method error .

what am i doing wrong ?

Update : Here the revert method in the controller

okay but then this is the revert method i got in the controller

def revert
  @version = Version.find(params[:id])
  if @version.reify
    @version.reify.save!
  else
    @version.item.destroy
  end
  link_name = params[:redo] == "true" ? "undo" : "redo"
  link = view_context.link_to(link_name, revert_version_path(@version.next, :redo => !params[:redo]), :method => :post)
  redirect_to :back, :notice => "Undid #{@version.event}. #{link}"
end

Answer 1

As Dave Newton said in the comments (+1), this belongs in a helper.

in helpers/pages_helper.rb :

module PagesHelper
  def undo_link
    # ...define view_context here...
    view_context.link_to("undo", revert_version_path(@page.versions.scoped.last), :method => :post)
  end
end

Note that you will need to define view_context before this will work, either in the space indicated, passing it in as an argument, or by using an instance variable accessible to the view at the time the helper method is called.

To call it in a view:

<%= undo_link %>

If you do this...

"#{undo_link}"

...you will get this:

 "<a href="/revert/version/path/...">undo</a>" # <= surrounded by quotes!

which will not work .