Question

I have a block of code that looks like this:

def create_page_object(url)
  begin
    page = Nokogiri::HTML(open(url))
  rescue
    puts "page not loaded"
  end
end

and then I call it via:

result.each do |url|
  page = create_page_object(url)
  content = make_content(page)
end

Now, in the terminal I see “page not loaded” and then Ruby blows up on me. How can I say, “If page not loaded, stop and go to the next each item”.

Update:

A Scientific Definition of Blowing Up:

test.rb:70:in `get_title': undefined method `xpath' for nil:NilClass (NoMethodError)
    from test.rb:40:in `block (2 levels) in process'
    from test.rb:35:in `each'
    from test.rb:35:in `block in process'
    from test.rb:32:in `upto'
    from test.rb:32:in `process'
    from test.rb:138:in `<main>'

What I believe is happening is because the is not being loaded, it there is no page variable set, which is nil and being throw into the make_content function.

Answer 1

The rescue block is returning the output of puts (which is nil), you have to make sure you have a document before working with it. Note also that in the rescue you should explicitly return nil to make clear what is the method returning in that branch. I’d write:

def create_page_object(url)
  begin
    page = Nokogiri::HTML(open(url))
  rescue
    puts "page not loaded"
    nil
  end
end

result.each do |url|
  if (page = create_page_object(url))
    content = make_content(page)
  end
end

I don’t know your especific needs, but it’s usually a bad idea to do “pre-emptive” rescues. Rescue when you have something useful to do, otherwise you’re preventing higher levels to do so.