Question

I’ve been hammering out some methods and testing them in the console. The problem is that an error occurs when running on the server. Specifically, the first method below triggers this NoMethod error:

undefined method `text' for nil:NilClass

Here’s the code. It’s from the webpage.rb file, which has a uri column.

def download_page_title
  page_as_xml.at_css('title').text
end

def page_as_xml
  page_as_xml ||= Nokogiri::HTML(open(page_uri))
end

def page_uri
  base_uri = Site.find_by_id(self.site_id).homepage #always has "/" at end
  if self.url == base_uri
    page_uri = base_uri
  else
    page_uri = "#{base_uri}#{self.url}"
  end
end

Any idea what I’m doing wrong? Also, any idea why things go smoothly in console but derail on the server?

EDIT: Here’s an example of what I’m doing in console.

1.9.3p194 :262 > a = Webpage.new( url: "http://www.cnn.com/", site_id:165)
 => #<Webpage id: nil, url: "http://www.cnn.com/", site_id: 165, created_at: nil, updated_at: nil, title: nil> 
1.9.3p194 :263 > a.download_page_title
  Site Load (0.3ms)  SELECT "sites".* FROM "sites" WHERE "sites"."id" = 165 LIMIT 1
 => "CNN.com - Breaking News, U.S., World, Weather, Entertainment & Video News" 

Answer 1

This means that page_as_xml.at_css is returning nil, and you’re then trying to call .text on that nil object.

So, figure out why that’s returning nil. For example, does the page you’re downloading not specify a title tag that is accessible via CSS selectors? Is the page blank or return no result? Does it return an error status (something not in the 2xx HTTP status range)?

To say it another way, there’s probably an upstream difference between the pages you’re using for testing versus what the server is actually getting.

You might need to handle (or throw an exception, or log/report) pages that return nil from a call to page_as_xml.at_css – that really depends on what your software needs to do.