Time comparison trouble with Rails

Question

I have a very simple task at hand. If the last time a record was updated has been longer than 15 minutes, display a button. Otherwise, don't display the button.

The field is a datetime.

My view code:

<% if @object.display_button? -%>
  my button
<% end -%>

My display button method on that object:

def display_button?
  return false if last_updated.nil?
  if Time.now - last_updated > 15.minutes
    true
  else
    false
  end
end

I also have this unit tested, which are passing, but when it comes to the implementation, it doesn't seem to work.

Is my logic correct or would there be a better way of accomplishing this?

Answer 1

if last_updated < 15.minutes.ago

The minutes method returns an integer I believe, and subtracting time object yields another time object. So your expression compares an int to a time and does something that you dont expect.

15.minutes.ago yields a time object that can be directly compared to another time object.

---

Also, never ever do if (something) return true; else; return false in ruby. Your method will return the value of that last expression executed in it, so you can vastly simplify that entire method:

def display_button?
  last_updated && last_updated < 15.minutes.ago
end

Isn't that easier to read?