search for: groups_files

Hi, I have three Models: User, Group and File. User habtm groups and Group habtm Files How can I find all files that a particular user has access to? eg user.groups.files ? As user.groups returns an array, the above doesn''t work. Id like to find the files for all groups in that array, without adding any code to the User model. Thanks in advance PS I just posted this in the