Rails 3.2 undefined method `key?' for nil:NilClass

I am a newbie to RoR and got the same error while going through RoR "Getting started guide".

This may sound silly, but others might make the same mistake as I am, so posting what I noticed in RoR from newbie's eyes,

validates :name,  : presence => true

Note ": presence", it should be ":presence". Now the Rail throws a Syntax error

 C:/blog/app/models/post.rb:4: syntax error, unexpected ':', expecting keyword_end validates :name,  : presence => true

But if you "Refresh" Your browser, it hides the syntax error, instead gives

undefined method `key?' for nil:NilClass

It seems Rails caching is the culprit. :)

This may not be your issue as it sounds like you already had working code to begin with, but for future reference for others, I ran into the same error due to a simple typo inside my model code, like so:

class Foo < ActiveRecord::Base    validates :content, :length => { maximum => 10 }end

which should have been:

class Foo < ActiveRecord::Base    validates :content, :length => { :maximum => 10 }end

Note the "maximum" vs. ":maximum" -- this resulted in the exact nil error above, and went away when I fixed that typo.

Not sure if this is the same bug, but I was having a similar issue. On a first load of a buggy model, Rails responds with a Routing error and then for the requests coming afterwards it responds with undefined method 'key?' for nil:NilClass and same stack trace.

This looks to be a bug with Rails class caching, but can get around by enabling class caching or disabling on change class reloading.

config.cache_classes = true

or

config.cache_classes = falseconfig.reload_classes_only_on_change = false