echo if variable is defined in ruby/erb
If you want to display nothing if a
is not defined :
<%= a if defined?(a) %>
Also what you can do is set some default to a
at the beginning of your partial if it's not defined. This way, you're assured that a
won't crash on you and you don't have to test if it's defined everywhere. I prefer this way personally.
CAUTION : if you set a
to false
when you pass it to the template, it'll be reassigned to ""
in my example .
<% a ||= "" %>
#Then do some things with it. No crash!
<%= a %>
<%= a*10 %>
<%= "Here's the variable a value: #{a}" %>
defined?
is the ruby equivalent to isset()
.
<%= defined?(a) ? a : 'some default' %>