Helper - undefined method `gsub' for nil:NilClass

Question

I have this function

application_helper.rb

def nl2br(s)
  s.gsub(/\n/, '<br/>')
end

View

<%= nl2br(@event.rules).html_safe %>

Error:

undefined method `gsub' for nil:NilClass

At times the content can be nil so which is the best way to handle it?

When I add unless s.nil? in the function I get html_safe undefined method error.

Answer 1

(Updated 2019)

With modern Ruby (2.3+), you can use the safe navigation operator:

def nl2br(s)
  s&.gsub(/\n/, '<br/>')
end

If s is nil, s&.gsub will fall back to nil, which will then output as empty string.

---

(Original answer from 2015)

Simple trick, just use an OR to setup a default:

def nl2br(s)
  (s||'').gsub(/\n/, '<br/>')
end

Alternatively, since nil.to_s evaluates to an empty string, you can do:

def nl2br(s)
  s.to_s.gsub(/\n/, '<br/>')
end