ruby on rails - Why isn't method defined in application_helper available to use in the view?

Question

When I put this in the application_helper.rb, it is available to use in the view

def foo
  "bar"
end

But when I put this in application_helper.rb it is not available to use in the view (instead: NoMethodError undefined method)

def nice_datetime 
  self.strftime('%d %b %-I:%M%p %Z')
end

Why is the first method available in the view and the second method not available in the view?

Answer 1

The self part is the problem, it is referencing the view itself* and that doesn't have a method called strftime. You can fix it somewhat by doing

def nice_datetime(date)
  date.strftime('...')
end

I would however urge you to look into localization. Which would work something like this, just a very basic setup.

# config/locales/en.yml
en:
  time:
    formats:
      short: "%H:%M"

<p><%= l Time.now, format: :short %></p>

---

* That might not be strictly true, I can't remember exactly how helpers are included in the view files, but for sake of this argument is close enough.