Using Rails helpers to render partials

Question

From my understanding, helpers are mainly used to clean up views from some view-specific logic.

But on my currently new project (legacy application), I've stumbled upon a lot of helpers that look like this

def itemprepare
  render :partial => 'items/itemlist_summary'
end

Is this correct? Rendering a partial to me seems like something you would want to do in the view, as it doesn't include any logic that needs to be abstracted.

Should I just inline all of these helpers?

Answer 1

Rendering a partial doesn't belong in a helper. Helpers should help you to do things that contain logic. Logic doesn't belong in the controller unless it's logic to render partials and decide if something should be displayed or not.

Answer 2

Although you generally shouldn't use helper methods to render partials, I can see how in some situations that might be necessary. For those circumstances, you need to use the concat method:

def itemprepare
  concat(render(:partial => 'items/itemlist_summary'))
end

Answer 3

Like Ajedi32 says, partials use belongs to views but sometimes it's useful to use them in helpers. I hope it's useful to show what I've done in my application:

I've been following the excellent article Thinking of Rails Helper to help DRY our view . I'm using Jquery Mobile with a fixed header, nav-bar, navigation panel and a footer.

In every page I need to include the footer and the navigation panel, so usually it would have been:

  <div data-role="footer">
    <h4>Page Footer</h4>
  </div><!-- /footer -->
  <%= render "shared/nav_panel" %>
</div><!-- /page -->

at the end of each page.

Then I refactored the render partial into the application helper and now it is:

  # app/helpers/application_helper.rb
  def page_footer
    footer = content_tag :div , :"data-role" => "footer" do
      content_tag :h4, "Page Footer"
    end
    nav_panel = render(:partial => 'shared/nav_panel')
    footer + nav_panel
  end

and in the view I just call:

<%= page_footer %>

This is just a short example; in reality the app has a footer that changes according to the logged-in status, user language, etc..

Answer 4

We have a couple of helpers like that in our project, but most of them are in our custom gem. Wrapping partial rendering with helper prevents application from knowing how the information is rendered and we can easily extend logic, change partial, or do whatever we want inside this helper as long as it renders requested part of the view. Sometimes these partial require some data that resides inside the gem itself and there is no need to expose it to application. So application calls helper method (sometimes without any parameters at all) that forms required parameters and locals and passes them to partial.

But when you're just rendering partial inside your application and you don't need any extensive logic around that rendering I don't think there's much use from creating new helper for every partial.