BUGFIX: more robust onebox implementation

lib/oneboxer.rb

@@ -35,12 +35,20 @@ module Oneboxer
     if c = Rails.cache.read(onebox_cache_key(url))
       c[:onebox]
     end
+  rescue => e
+    invalidate(url)
+    Rails.logger.warn("invalid cached onebox for #{url} #{e}")
+    ""
   end
 
   def self.cached_preview(url)
     if c = Rails.cache.read(onebox_cache_key(url))
       c[:preview]
     end
+  rescue => e
+    invalidate(url)
+    Rails.logger.warn("invalid cached preview for #{url} #{e}")
+    ""
   end
 
   def self.oneboxer_exists_for_url?(url)
@@ -110,9 +118,7 @@ module Oneboxer
   end
 
   def self.onebox_raw(url)
-    Rails.cache.fetch(onebox_cache_key(url)){
+    Rails.cache.fetch(onebox_cache_key(url), expires_in: 1.day){
-      begin
-
       # This might be able to move to whenever the SiteSetting changes?
       Oneboxer.add_discourse_whitelists
 
@@ -121,10 +127,11 @@ module Oneboxer
         onebox: r.to_s,
         preview: r.try(:placeholder_html).to_s
       }
+    }
   rescue => e
     Discourse.handle_exception(e, url: url)
-      end
+    # return a blank hash, so rest of the code works
-    }
+    {preview: "", onebox: ""}
   end
 
 end

spec/components/oneboxer_spec.rb

@@ -0,0 +1,10 @@
+require 'spec_helper'
+require_dependency 'oneboxer'
+
+describe Oneboxer do
+  it "returns blank string for an invalid onebox" do
+    Oneboxer.preview("http://boom.com").should == ""
+    Oneboxer.onebox("http://boom.com").should == ""
+  end
+end
+