TemplateError: wrong number of arguments in default_url_options()

Posted by Wes in Ruby on Rails

Jan
30

During an app upgrade to Rails 2.2.2, I came across this error that baffled me for a few minutes:

ActionView::TemplateError
    (wrong number of arguments (0 for 1)) on line #34
    of app/views/account/_dashboard_header.rhtml:

34: <%= link_to 'My Dashboard', my_dashboard_url >

Checking out the backtrace:

(eval):3:in `default_url_options'
(eval):3:in `my_dashboard_url'
app/views/account/_dashboard_header.rhtml:34

Confusing. Why would this named route suddenly stop working? I did a search for default_url_options and found that I had overridden that function:

if production_mode?
  def default_url_options()
    { :protocol => 'https://' }
  end
end

Aha! Back in the day, default_url_options didn’t have any default options, so I wasn’t bothering to merge my desired options with the options parameter. I fixed it with a reverse_merge so any passed-in options would still exist.