CODEWITHSUNDEEP
ruby
Michael Hill
Michael Hill

Reputation: 85

Undefined method each for nil:NilClass in erb template

I'm trying to loop through and array and have checked to make sure it is being passed correctly to the template, yet am hitting the error.

The template:

<% if defined?(source[:blacklist]) %>
   "blacklist": [
    <% source[:blacklist].each do |listed| %>
    "<%= listed %>"
    <% end %>
  ],
<% end %>

output of source[:blacklist] when no loop:

"[\"/var/log/httpd/access.log*\", \"/var/log/httpd/error.log*\", \"/var/log/httpd/ssl_request_log\", \"/var/log/httpd/access_log\", \"/var/log/httpd/error_log\"]"

error:

undefined method `each' for nil:NilClass

Upvotes: 0

Views: 1953

Answers (2)

nibbex
nibbex

Reputation: 361

Your array is not present, if it was it would actually be a string.

Using defined?(source[:blacklist]) presents an issue as it will return true if it's not an array, e.g. defined? nil is "nil" which is truthy.

Step 1: convert to array

If you cannot change how the data is being generated, parse it into a Ruby array, defaulting to an empty array if there is an unexpected data or none at all.

blacklist = source[:blacklist].gsub(/(\­[\"|\"\])/­, '').s­plit('", "') || []

Step 2: loop if the array exists and with content

<% if not blacklist.empty? %>

Upvotes: 1

SteveTurczyn
SteveTurczyn

Reputation: 36860

If source[:blacklist] is nil then defined? source[:blacklist] will return the string "method" and that's "truthy".

So it will fall through and you'll get the error you see... Undefined method each for nil:NilClass

When you say "output of source with no loop"... is that in the controller or did you check the output in the erb file? It could be the value's not being passed to the erb, and you typically want to use instance variables to pass data to html.erb files.

Also, you should note that the output you show for source[:blacklist] is actually a string, not an array, so even if it was passed you would still get an error on the each method.

Upvotes: 0

Related Questions