Question

我一直在使用我们的rails 2.3应用程序中的一个控制器，并且我遇到了使用helper_method中指定的实例变量的问题。最初，情况是这样的：

home_controller.rb:
class HomeController < ActionController::Base
  def index
  end

  def popular
    @popular_questions = PopularQuestion.paginate :page => params[:page],
                                                  <some complex query>
  end
end

home_helper.rb:
module HomeHelper
  def render_popular_questions
    @popular_questions = PopularQuestion.paginate :page => 1, 
                                                  <some complex query>
    render :partial => 'popular'
  end
end

home/index.html.haml
-cached do
  .popular=render_popular_questions

home/popular.html.haml
=render :partial => 'popular'

home/_popular.html.haml
-if @popular_questions.length > 0
  <show stuff>

点击/或/热门显示了相应的热门问题框。

现在，由于查询非常复制，并且由于paginate默认使用正确的页面，因此我将其重构为：

home_controller.rb:
class HomeController < ActionController::Base
  helper_method :get_popular_questions

  def index
  end

  def popular
    get_popular_questions
  end

  private

  def get_popular_questions
    @popular_questions = PopularQuestion.paginate :page => params[:page],
                                                  <some complex query>
  end
end

home_helper.rb:
module HomeHelper
  def render_popular_questions
    get_popular_questions
    render :partial => 'popular'
  end
end

现在当我去/时，我得到了

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.length

在home / _popular.html.haml

的第1行中被提升

模板似乎无法访问从帮助程序内调用的helper_methods中设置的变量。我在某个地方犯了错误吗？如果没有，我如何使用助手的helper_method中指定的实例变量？

Answer 1

将它们作为参数和局部变量传递：

home_controller.rb:
class HomeController < ActionController::Base
  helper_method :get_popular_questions

  def index
  end

  def popular
    @popular_questions = get_popular_questions
  end

  private

  def get_popular_questions
    # remember that the final statement of a method is also the return-value
    PopularQuestion.paginate :page => params[:page],
                                              <some complex query>
  end
end

home_helper.rb:
module HomeHelper
  def render_popular_questions
    questions = get_popular_questions
    render :partial => 'popular', :locals => {:questions => questions}
  end
end

现在在你的部分，使用“问题”而不是“@popular_questions” 只需确保“热门”的主模板也需要填充此局部变量。

如何使用帮助程序中helper_method中指定的实例变量？

1 个答案: