ActiveRecord Question across Tables

Hi All,

I know the answer to this may be simple but I cannot think of it! First
let me explain the problem.

I have the following tables and relations:
log_entries <n…n> users
log_entries <n…1> users
users <n…n> groups

groups < residence1, residence2 (non-normalized by design)

I would like a way to get an array of user id’s (or user objects) from a
given log entry such that the array contains one element for each user
which is a member of a group which has a residence in common with the
user who created the log entry.

What I currently have is a messy list of code segments such as:

groups = self.user.groups

residences = []
groups.each do { |group|
residences << group.residence1
residences << group.residence2
}

users = []
residences.each do { |residence|

}

Can anyone please explain the best (or just a better) way of doing this
please. I am falling very much in love with Rails, it is the first
framework I have really got to grips with and have heard lots about its
great community!

Many thanks in advance,

James A.s