Flash[:error] and Cookie Sessions

We still have a few apps that store the errors collection of an ActiveRecord object in the flash[:error] hash. This always worked fine, but since switching to cookie store, sometimes we get an exception because the cookie data is greater than 4KB.

What happens is the ActiveRecord::Base object is stored in the ActiveRecord::Errors object. If this object is too big, the exception is raised.

I monkey patched the FlashNow object to nil the @base ivar in flash.now. Here is the code:

class ActionController::Flash::FlashNow
  def []=(k, v)
    new_v = v.clone
    new_v.instance_variable_set(:@base, nil) if v.is_a?(ActiveRecord::Errors)
    @flash[k] = new_v
    @flash.discard(k)
    v
  end
end

class ActionController::Flash::FlashHash
  def []=(k, v)
    new_v = v.clone
    new_v.instance_variable_set(:@base, nil) if v.is_a?(ActiveRecord::Errors)
    keep(k)
    super(k, new_v)
  end
end

This takes care of the problem without affecting any other part of the app. Just drop this code in an initializer and bob's your uncle.
 

1 Comment

Jason Seifer said on August 06, 2008

That’s awesome — a really creative work-around. You should try and get something like this in core.