ruby - undefined method `content_for' in presenter rails -

i using presenter view in rails display data saved in yml file. (i18n gem)

this controller-

class documentscontroller < applicationcontroller   def index     @presenter = documentpresenter.new   end end 

this view-

= @presenter.viewname 

and presenter-

class documentpresenter   def viewname     content_for :secondary_nav_title       t('documents')     end   end end 

the error says:

undefined method `content_for'

why doesn't rails recognize content_for in presenter?

the content_for helper method should not used in model violates mvc pattern.

if must use it, though not reccomended, can add @ bottom of model.

def helpers      actioncontroller::base.helpers end 

then call content_for use

class documentpresenter   def viewname       helpers.content_for :secondary_nav_title          t('documents')       end   end end