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You have a nil object when you didn't expect it!

Posted on 2009-05-18
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Last Modified: 2013-11-13
Have a look at the code below and see if you can point me in the right direction...I'm certain it is something fundamental.
in my controller file:
 
require "RubyGems"
require "feed_tools"
		
def user_data
      @feed = FeedTools::Feed.open(params[:feed_url])
      # You can first test it with a static feed url like this
      @feed = FeedTools::Feed.open('http://www.sphred.com/combined_feed')
end
 
 
Error in browser:
 
You have a nil object when you didn't expect it!
The error occurred while evaluating nil.link
 
Extracted source (around line #105):
 
102: 	  
103: 	  <div>
104:     <h3>
105:       <a href="<%= h @feed.link %>">
106:       <%= @feed.title %></a>
107:     </h3>
108:     <p><%= @feed.description %></p>

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Question by:envythe
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2 Comments
 
LVL 12

Accepted Solution

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cminear earned 125 total points
ID: 24416071
The long and short of it is that @feed is either not being set, or being set to nil, and thus trying to apply the 'link' method to a nil doesn't work.  However, I'm actually surprised you are seeing the error that you are.  Based on my quick tests, I would expect you to be seeing Exceptions being thrown by either of the "FeedTools::Feed.open" calls you gave.  

Just using IRB, I try:
  feed = FeedTools::Feed.open(nil)
I get this exception.
  NoMethodError: undefined method `scheme' for nil:NilClass
So if you called the 'user_data' action with no 'feed_url' parameter passed in, that should have thrown an exception.

If you did pass in a 'feed_url' parameter, then going to the next line, I tried:
  feed = FeedTools::Feed.open('http://www.sphred.com/combined_feed')
I get this exception:
  FeedTools::FeedAccessError: Socket error prevented feed retrieval
'www.sphred.com' does not exist (at least not from where I'm doing web and DNS requests).

So the only explanation that would account for what you are seeing is that your environment has some sort of global 'rescue' applied to the controller methods, but at the same time, the 'rescue' doesn't apply to the rendering of the page.  Are you not sharing some part of your code with us?
0
 

Author Closing Comment

by:envythe
ID: 31583667
Appreciate the help - was able to work through it with your comments
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