In ruby on rails when doing session[:foo] = nil it leaves an entry named :foo in the session object. How can you get rid of that single entry from the session object?
+1
A:
As the Session is a Ruby CGI::Session and not a Hash, calling delete will actually delete session. Delete takes no parameters - this is my you're getting the "wrong number of arguments (1 or 0)" message when you try what hyuan suggests.
The generally accepted way to clear a session entry is with session[:foo] = nil as you suggest. It is far from ideal, but statements like session[:foo].nil? will behave as expected.
I really wish it behaved like a normal Hash ... but it doesn't.
RichH
2009-03-26 07:58:15
+3
A:
Actually there is a way to get delete a value from the session. Like RichH said the session variable is a CGI::Session instance. When enter something like session[:foo] it is actually looking that symbol up in a @data instance variable in the session object. That data variable is a hash.
EDIT: There is a data instance variable in the CGI::Session class. If you go to the docs and look at the source code for the []= method you'll see that there is a @data member.
So to delete session[:foo] all you have to do is access that @data variable from inside the session
session.data[:foo]
Now to delete it:
session.data.delete :foo
Once you do this the there should be no more foo in your session variable.
vrish88
2009-03-26 08:10:24
Is that portable accross all of the session stores? It looks a little intimate as the data attribute isn't mentioned in the docs.
RichH
2009-03-26 08:19:59
I honestly don't know. I discovered it by using debugger and inspecting the session variable. I was able to find a little support for my answer though, http://tinyurl.com/cp7ntm, check out the last method where they assign session_data = @_session.data. That's the most I could find on it
vrish88
2009-03-26 09:14:02
I just updated my answer with a much better source for some documentation on the subject.
vrish88
2009-03-26 09:40:17
That's just the ActiveRecord store - if you look at the cookie store, memcache store, etc they don't have this attr_reader - http://github.com/rails/rails/blob/31ce92f7b5784bc5b6a441e88cd734c7b8b1c58f/actionpack/lib/action_controller/session/cookie_store.rb
RichH
2009-03-26 15:10:51
The way I understand it is that the CGI::Session:CookieStore is an extension of the CGI::Session class. So CookieStore would inherit everything in CGI::Session. When we modify the Session class (by adding @data to it) we inherit all those changes into the extensions that follow it (CookieStore)
vrish88
2009-03-26 16:23:41
@data isn't in the base Session class it's in the active record session store - that's the source you pointed to. The memcached session doesn't use @data, it uses an @cache to store the session contents. ActiveRecord does something different to. This is implementation specific.
RichH
2009-03-26 17:53:59
Ok @data may not be in the rdoc for CGI::Session but if you take a look at the actual code for the '[]=' method, http://tinyurl.com/djoltc, you'll see that a @data instance variable is created or written to. So for certain session stores Rails will overwrite the @data variable.
vrish88
2009-03-26 22:16:58
did this work for you?
vrish88
2009-04-01 20:56:51